The Context Of A Process
The context of a process consists of the contents of its (user) address space and the contents of hardware registers and kernel data structures that relate to the process. Formally, the context of a process is the union of its user-level context, register context, and system-level context.1 The user-level context consists of the process text, data, user stack, and shared memory that occupy the virtual address space of the process.
Freeboard Computation
Basic freeboards are given in the rules which are dependent on the length and type of vessel. Ships are divided into types 'A' and 'B'. Type 'A' ships are those which are designed to carry only liquid cargoes in bulk, and in which the cargo tanks have only small access openings closed by watertight gasketed covers of steel or equivalent material. These vessels benefit from the minimum assignable freeboard. All ships which do not come within the provisions regarding Type 'A' ships are considered...
Stall Test Procedure
Interpreting stall test results A typical stall test maximum engine speed could be 2300 revmin 100. If the actual stall speed differs from the recommended value, the table should be used as a guide to trace the fault. The stall test therefore helps to determine if the fault is due to the engine, the converter or the transmission assembly.
33 Basic Components Of An Energy Audit
An initial summary of the basic steps involved in conducting a successful energy audit is provided here, and these steps are explained more fully in the sections that follow. This audit description primarily addresses the steps in an industrial or large-scale commercial audit, and not all of the procedures described in this section are required for every type of audit. The audit process starts by collecting information about a facility's operation and about its past record of utility bills....
Detritus Tanks
Detritus tanks remove a mixture of grit and organic matter. The width and shape of the grit chamber are not critical with this design, but the surface area (which relates to settling velocity) is. The area requirements are proportional to the settling velocity of the grit particle and to the waste-water flow rate. The settled grit is conveyed to a common collection sump. A raking or conveying mechanism washes and removes the grit from the chamber in a clean and drained condition, and the...
Melting and pouring the babbitt
CASUALLY watching, a workman pouring babbitt metal into the bearing shell does not impress the observer as requiring any skill on the part of the operator. Neither does this operation seem to be such as to require any special attention or careful supervision. However, this impression is misleading,, for to produce reliable and dependable babbitted bearings, many little details, must be thoroughly mastered. Melting Babbitting outfits vary from an old kettle heated on the blacksmith forge, to a...
Recommendations on metacentric height
Ideally, the stability should be assessed using the complete righting arm curve, but since it is impossible to calculate righting arm curves without the outline design, more easily determined GM values are given as a function of the ship type, Table 1.4. If a vessel has a GM value corresponding well to its type, it can normally be assumed (in the early design stages) that the righting arm curve will meet the requirements. Table 1.4 Standard GM for 'outward journey', fully loaded Table 1.4...
Lloyd's Register Classification
All ships classed by Lloyd's Register of Shipping are assigned one or more character symbols. The majority of ships are assigned the characters 100A1 or 100A1. The character figure 100 is assigned to all ships considered suitable for sea-going service. The character letter A is assigned to all ships which are built in accordance with or accepted into class as complying with the Society's Rules and Regulations.
How To Cook Calamari Steaks
Not many people know that for steak recipes, calamari steaks can be a rare yet delightful treat. For fear of avoiding underdone calamari dishes, most people just overdo them making the meat taste rubbery in the process. However, when done properly, calamari steaks are truly mouth-watering. Something you can truly enjoy Buying Calamari SteaksFor someone not very familiar with calamari dishes yet, the best thing to try is one that is frozen.
How Scented Flameless Candles Work
The convenience flameless candles offers, especially scented flameless candles, makes it easier for us to go on with other activities of our daily lives. But for the inquisitive mind, a question arises as to how exactly scented flameless candles work. Is the technology behind these unique candles complicated Do scented flameless candles contain little machines trapped inside each candle Can the technology of scented flameless candles be replicated Anatomy of scented flameless candles From afar...
Schwedler Dome Horizontal Polygonal Rings
A Schwedler dome also consists of meridional ribs connected together to a number of horizontal polygonal rings to stiffen the resulting structure so that it will be able to take unsymmetrical loads (Figure 24.14b). Each trapezium formed by intersecting meridional ribs with horizontal rings is subdivided into two triangles by a diagonal member. Sometimes the trapezium may also be subdivided by two cross-diagonal members. This type of dome was introduced by a German engineer J.W. Schwedler in...
A CupandBob Couette Viscometer
As the name implies, the cup-and-bob viscometer consists of two concentric cylinders, the outer cup and the inner bob, with the test fluid in the annular gap (see Fig. 3-2). One cylinder (preferably the cup) is rotated at a fixed angular velocity (Q). The force is transmitted to the sample, causing it to deform, and is then transferred by the fluid to the other cylinder (i.e., the bob). This force results in a torque (T) that can be measured by a torsion spring, for example. Thus, the known...
Minimum Design Metal Temperature MDMT
This MDMT procedure is used to determine the lowest permissible temperature for which charpy impact testing is or is not required. The ASME Code requires this be determined for every pressure vessel and the MDMT be stamped on the nameplate. While every pressure vessel has its own unique MDMT, this may or may not be the MDMT that is stamped on the nameplate.
How To Build A Mini Catapult
A catapult is a war machine used to fling a kind of projectile. Mini catapults are great toys which are very fun to play with. The easiest and simplest one that you can possibly make only involves a spoon. The only thing you need to do is leverage it using your hands. Another type of mini catapult can also be created by you, the type which is more fun when used and one which looks even more interesting.
Piston Rod Runout
Piston rod runout is a measure of how well the cylinder is lined up with the frame and, also, how well the internals of the compressor piston, rod, crosshead are lined up with each other and the frame and cylinder combination. This runout is checked and adjusted with all parts cold the ambient temperature should be in the 60 -68 F range. Prior to performing runout measurements, cylinder and support, cylinder frame head, and doghouse nuts should be properly set or torqued. Oil scraper and...
Membrane Stress Analysis
Pressure vessels commonly have the form of spheres, cylinders, cones, ellipsoids, tori, or composites of these. When the thickness is small in comparison with other dimensions (Rm t > 10), vessels are referred to as membranes and the associated stresses resulting from the contained pressure are called membrane stresses. These membrane stresses are average tension or compression stresses. They are assumed to be uniform across the vessel wall and act tangentially to its surface. The membrane or...
Ammonia Process Flow Diagram
Used with permission of Simulation Sciences Inc. excess of 21 bar are required to achieve sufficient conversion. Conversions of 20 -25 ammonia per pass are achieved. However, the conversion of hydrogen per pass is still less than 30 , therefore, the process requires a large recycle of unreacted gases. The converted vapor product is cooled by ammonia refrigeration in the primary separator to condense the ammonia product. A purge is removed from the...
How Are Paintballs Made
What is Paintball Paintball is a sport where the competing players eliminate opponents by targeting and hitting them with capsules that contain paint called paintball from a gun specially designed for the game called the paintball marker'. Games can be played indoors or outdoors with varied field sizes. The game field is designed with artificial terrains that the players can use for strategic play.
How Can I Find Someone's Cell Phone Number
When one wants to know some secrets about someone, they often imagine that the cell phone number of a person can reveal the information which is needed. Such persons would ask themselves how someone's cell phone number can be found. Some think about it when they want to investigate the credibility of a person, such as a spouse or a friend. However it is almost impossible to get a cell phone number as compared to landline numbers.
Hydraulic Balancing Devices
If all the single-suction impellers of a multistage pump face the same direction, the total theoretical hydraulic axial thrust acting toward the suction end of the pump will be the sum of the individual impeller thrusts. The thrust magnitude will be approximately equal to the product of the net pump pressure and the annular unbalanced area. Actually, the axial thrust turns out to be about 70 to 80 percent of this theoretical value. Some form of hydraulic balancing device must be used to balance...
Elementary aeroelasticity
Aircraft structures, being extremely flexible, are prone to distortion under load. When these loads are caused by aerodynamic forces, which themselves depend on the geometry of the structure and the orientation of the various structural components to the surrounding airflow, then structural distortion results in changes in aerodynamic load, leading to further distortion and so on. The interaction of aerodynamic and elastic forces is known as aeroelasticity. Two distinct types of aeroelastic...
52 Product development models 521 Overview of product development models
Product development models are the driving force for delivering the product to market on time and at the right cost. In general, the models in the literature can be divided into just two types sequential and concurrent. Each has its own characteristics, but there are several requirements that a new product development model should fulfil (Sum, 1992) It must be scaleable as organizations change size constantly The model will probably be introduced incrementally, perhaps into one team, and then...
Holding the Work
As shaper operations are concerned primarily with small work-pieces, the work is usually held in either a vise or a chuck. These holding devices are auxiliary to the table or machine. It is important to place the stops T-bolts properly. If the work were laid on the table without the stops to resist the thrust of the cutting tool on the cutting stroke, the cutting tool would push the work rather than cut it. Large pieces of work that cannot be held in a vise should be fastened to the table. In...
How To Address An Envelope
With the advent of the internet people stopped sending letters to their friends and relatives. Letters were replaced by emails. Still for official purposes business letters are sent. With this arises the need to learn how to address an envelope. If proper care is taken while addressing an envelope, the letter will reach the correct destination and in time. The business envelope is the first impression of the sender in the eyes of the receiver.
Brass Plating
The largest use of brass plating is for decorative applications. Copper-zinc alloys that contain more than 60 Cu have distinct colors, depending on the composition. The 60Cu-40Zn alloys are pale yellow, sometimes with a brown cast. Alloys with compositions from 70Cu-30Zn to 80Cu-20Zn are yellow, with only slight color variations over this range. The 85Cu-15Zn alloys are darker and resemble gold. The 90Cu-10Zn alloys are darker still, with a reddish, bronze-like cast....
10000 20000 30000 40000 50000 60000 70000 60000 90000 100000
Series and parallel operation centrifugal pumps. slightly more than one single pump. The maximum flow rate with two pumps in series will be 2,594 gpm or 89,439 b d. The maximum flow rate for one pump will be 1,917gpm or 66,092 b d. For system rates between 66,092b d and 89,439b d, pressure throttling will be necessary to match the pump performance to the system curves, unless the pumps are equipped with variable speed drives. If throttling is necessary, it may be minimized by...
Engineering Of Pumping System Requirements
The first step is to define the requirements and conditions under which the equipment will operate. Fluid Type A thorough description of the fluid to be handled must be developed. This includes properties such as viscosity, density, vapor pressure, corrosiveness, erosiveness, volatility, flammability, and toxicity. Depending on the process and the system, some or all of these properties may have an important effect on the pump and system design. For example The corrosiveness of the fluid will...
811 Starting a gyrocompass
As has been previously stated, from start-up a gyrocompass needs time to settle on the meridian. The time taken depends upon the make, model and the geographic location of the compass, but in general it is between one and several hours. The duration also depends upon whether the gyro wheel is already rotating or not. If the compass has been switched off, it will take much longer to bring the compass into use. Inputting the ship's heading to reduce the initial error factor can reduce the time...
Nomenclature
ABT Area of transverse cross-section of a bulbous bow Ae Expanded blade area of a propeller Ao Disc area of a propeller n D2 4 BM Height of transverse metacentre (M) above centre of buoyancy (B) BN Beaufort number CB Block coefficient V (L B T) Cbd Block coefficient based on depth CBA Block coefficient of aftbody CBF Block coefficient of forebody CDH Volumetric deckhouse weight CF Frictional resistance coefficient CM Midship section area coefficient AM (B T) CM Factor taking account of the...
Centrifugal Pump Reference
Determination of Pump Efficiencies from Fluid Temperature Rise. Presented at the 7th Annual Spring Pipeline Conference, Houston, Texas, May 14, 1956, under the auspices of the American Petroleum Institute's Division of Transportation. Published in the Division's Vol. 36 5 1956. 2. Cooper, P., and Reshotko, E. Turbulent Flow Between a Rotating Disk and a Parallel Wall. AIAA Journal. Volume 13, No. 5, May 1975, pp. 573 578. 3. Sabersky, R., and Acosta, A. J....
Selecting Compressor Motors
The first step in selecting motors for large compressors (1,500 hp and over) is to determine the motor voltage, speed, and enclosure type. Motor voltage selection is determined by economics and by the availability of adequate system capacity to permit motor starting without excessive voltage drop. Restrictions by the utility or by the size of the plant's generating capacity may limit the maximum drop to less than 20 . In some cases, system dips as small as 5 or less may be the maxi mum...
Impingement And Impaction
The impingers previously described for sampling gases and vapors (see Figure 5.10.3) can also be used for the collection of particles and, in fact, were originally developed for that purpose. However, in ambient air sampling, they are not used because their collection efficiency is low and unpredictable for the fine particles present in ambient air. The low sampling rates also make them less attractive than filters for general air sampling, but instances do arise when impingers can be...
Setting Piston End Clearance
Whenever the piston rod has been removed or even turned in or out of the crosshead, it is necessary to check the piston end clearance and make any adjustments necessary to restore it to the proper amount. If the piston has not been removed from the rod, the original clearance can easily be maintained by center punching both the rod and the crosshead and making a suitable scribing tool, as shown in Figure 4-39, before removing the rod from the crosshead. Note The length of the scribing tool will...
843 Other methods of separation control
Passive flow control through the generation of streamwise vortices is frequently used on aircraft and other applications. Some of the devices commonly in use are depicted * See the recent review by D. Greenblatt and I. Wygnanski (2000) 'The control of flow separation by periodic excitation', Prog, in Aerospace Sciences, 36, 487-545. Seifert and L.G. Pack (1999) 'Oscillatory control of separation at high Reynolds number', AIAA J., 37(9), 1062-1071. in Fig. 8.32. Figure 8.32a shows a row of...
Index Plate Diagram
An index plate can be used for any number of divisions that divides the number of holes in the plate equally. A plate with a larger number of holes than is required can be used if the number of holes is an exact multiple of the number of divisions required. In production work, it is safer to use a plate that has exactly the same number of holes as the required number because the possibility of making a mistake in indexing is reduced. Figure 14-1 shows the basic parts of an index plate that can...
Formation Volume Factor Of
Change of oil formation volume factor with gas in solution vs. oil In 1977, Standing's classic work 2 was reprinted 30 by the Society of Petroleum Engineers and an appendix was added by Standing that provides equations for several of the charts in the original work. Most of the equations were developed by simple curve fitting procedures. Some equations were based on computer solutions by other individuals details of this will not be presented here and the reader is referred to...
15 Midship section area coefficient and midship section design
The midship section area coefficient CM is rarely known in advance by the designer. The choice is aided by the following criteria (Fig. 1.18) Figure 1.18 Section area curves with constant displacement and main dimensions, but different midship area coefficients Figure 1.18 Section area curves with constant displacement and main dimensions, but different midship area coefficients Increasing CM while keeping CB constant will usually have the following effects C Increased run length decreased...
The midships coefficient Cm
The midships coefficient to any draft is the ratio of the transverse area of the midships Section Am to a rectangle having the same breadth and depths. In Figure 9.3 the shaded portion represents the area of the midships section to the waterline WL, enclosed in a rectangle having the same breadth and depth. The prismatic coefficient of a ship at any draft is the ratio of the volume of displacement at that draft to the volume of a prism having the same length as the ship and the same...
Shell Plating
The bottom and side shell plating consists of a series of flat and curved steel plates generally of greater length than breadth butt welded together. The vertical welded joints are referred to as 'butts' and the horizontal welded joints as 'seams' see Figure 17.1 . Stiffening members both longitudinal and transverse are generally welded to the shell by intermittent fillet welds with a length of continuous weld at the ends of the stiffening member. Continuous welding of stiffening members to the...
Wartsila
Introduced in 1992, the 200 mm bore 280 mm stroke Wartsila 20 engine (Figure 27.10) was designed primarily as a genset drive to replace the long-established Wartsila Vasa 22 but small-ship propulsion installations have also been logged. An output per cylinder of 130 kW to 165 kW was initially offered, depending on the nominal speed (720-1000 rev min), but subsequent power rises took the rating to 180 kW cylinder (end-1998) and 200 kW cylinder at 1000 rev min (2003). The rating increases were...
Main Features Of The Gz Curve
Certain features of the GZ curve are of particular significance and are useful parameters with which to define the stability possessed by a given design. They include (a) Slope at the origin. For small angles of heel, the righting lever is proportional to the angle of inclination, the metacentre being effectively a fixed point. It follows, that the tangent to the GZ curve at the origin represents the metacentric height. (b) Maximum GZ. This is proportional to the largest steady heeling moment...
842 Periodic Dispersion Maps
A disadvantage of the DDF is that the average dispersion along the link is often relatively large. Generally speaking, operation of a soliton system at a wavelength where the average GVD is low should improve system performance since it reduces the timing jitter as well as the Raman-induced spectral shift. However, for constant-GVD fiber links, as the operating wavelength approaches the zero-dispersion wavelength, several factors affect the system performance considerably 112 . For example, the...
Industrial Crystallizers
Several types of crystallizers are commercially available. The choice of crystallizer depends on the material to be crystallized and the solvent, the method of crystallization, the product specifications, in particular the crystal size distribution, and the flexibility of the design in cases where products of various coarseness L50 must be crystallized on demand in the same equipment. Here only three large scale evaporative and cooling crystallizers will be discussed. These examples mainly...
Closed feed system
A closed feed system for a high pressure watertube boiler supplying a main propulsion steam turbine is shown in Figure 5.2. The steam turbine will exhaust into the condenser which will be at a high vacuum. A regenerative type of condenser will be used which allows condensing of the steam with the minimum drop in temperature. The condensate is removed by an extraction pump and circulates through an The condensate is heated in passing through the air ejector. The ejector removes air from the...
763 Inter axle with third differential
Description of forward rear drive axle (Fig. 7.27) A third differential is generally incorporated in the forward rear axle of a tandem bogie axle drive layout because in this position it can be conveniently arranged to extend the drive to the rear axle (Fig. 7.27). Fig. 7.26 Relationship of relative speeds of double drive axles and the amount of transmission twist Fig. 7.26 Relationship of relative speeds of double drive axles and the amount of transmission twist Power from the gearbox...
Runner Line
Stiffleg derricks are extremely versatile in that they can be used in a permanent location as yard derricks or can be mounted on a wheel-equipped frame for use as a traveler in bridge erection. A stifleg derrick also can be mounted on a device known as a creeper and thereby lift itself vertically on a structure as it is being erected. Stiffleg derricks can range from small, 5-ton units to large, 250-ton units, with 80-ft masts and 180-ft booms. A guy derrick (Fig. 2.6) is...
Philips Stirling Engine
FtO. 12.4 Type 102C SlirliiiR-cnpincelecirie-powcr Rcneralingset after Mcijei 1969c FtO. 12.4 Type 102C SlirliiiR-cnpincelecirie-powcr Rcneralingset after Mcijei 1969c miles al a speed of 4.6 m s 9 knots on the Dutch canals. Viewers on shore were apparently startled at the sight of the boat with several passengers moving without noise through the water with no visible means of propulsion. The engine was concealed under a cardboard box. The decision was made in 1952 to start production of the...
Imperforate Bowl Basket Knife Centrifuge
This centrifuge, the simplest type in general use, is suited for soft or fine solids that are difficult to filter and waste that varies in concentration and solids characteristics. That design can be either a top-driven suspended bowl or an underdriven bowl with three-point casing suspension the drive can be a hydraulic or an electric motor. A 12- or 14-in diameter bowl is often used for test work, whereas 30 to 48 in is the range of commercial units. Older designs operate below 1000 G (G is...
Taper ratio
The selection of taper ratio i.e. tip chord divided by aircraft centreline root chord involves several aerodynamic considerations. A constant chord rectangular planform may be easier and cheaper to manufacture than a tapered wing but it is aerodynamically and structurally less efficient. Aerodynamically an elliptical planform is regarded as ideal because it reduces the tip vortex effect. The geometry of some straight tapered layouts can be shown to approximate to the elliptical shape and...
Factors That Influence The Rate Of Bioerosion
Although the solubilization of intact polymer as well as several distinct mechanisms of chemical degradation have been recognized as possible causes for the observed bioerosion of a solid, polymeric implant, virtually all currently available implant materials (Table 2) erode as a result of the hydrolytic cleavage of the polymer backbone (mechanism III in Fig. 2). We therefore limit the following discussion to solid devices that bioerode as a result of the hydrolytic cleavage of the polymer...
Curves Of Statical Stability
It was explained earlier, that it is usually convenient to derive cross curves of stability from purely geometric considerations by making use of an arbitrary Fig. 4.17 Curve of statical stability Fig. 4.17 Curve of statical stability pole about which to measure righting moments. It was also seen, that it simplifies the work in deriving stability curves if displacement is allowed to vary as the ship is inclined and if both displacement and righting lever are calculated for each waterline. For...
2 Statical Stability curves
The curve of statical stability for a ship in any particular condition of loading is obtained by plotting the righting levers against angle of heel as shown in Figures 16.4 and 16.5. Curve for a ship with positive initial metacentric height. Curve for a ship with positive initial metacentric height. From this type of graph a considerable amount of stability information may be found by inspection The range of stability. This is the range over which the ship has positive righting levers. In...
39 Components Of Stress And Strain
Because the moment MA and its corresponding components are all taken about point O, they are not producing any additional stress at this point. FIGURE 3.11 (a) Stress-strain diagram for A36 steel. (b) Portion of that diagram in the yieldins ranse. FIGURE 3.11 (a) Stress-strain diagram for A36 steel. (b) Portion of that diagram in the yieldins ranse. If another plane is cut through O that is normal to the y axis, the area surrounding O in this plane will be subjected to a different resultant...
Planning product realization processes
There are too many variations in the product realization process to provide much more than an overview. Product planning is driven by two processes - the sales process and the marketing process. The sales process promotes the organization's existing products and service and attracts enquiries, thus creating a need for an enquiry conversion process to convert customer enquiries into orders or contracts. This may require a project planning process in order to provide the customer with a viable...
427 Fixed firefighting equipment
Fixed fire-fighting equipment is permanently fixed in a building and is designed to work automatically in the event of a fire. Essentially it comprises a system of fixed pipes with discharge heads or points for the extinguishing medium at predetermined positions. The positioning of the discharge heads is determined by the type of building, its contents, the fire risk and the type of extinguishant and is normally to standards developed by fire insurers. Once installed and commissioned fixed...
Aircraft Downwash
5.2.3 Variation of velocity in vortex flow To confirm how the velocity outside a vortex core varies with distance from the centre consider an element in a thin shell of air (Fig. 5.12). Here, flow conditions depend only on the distance from the centre and are constant all round the vortex at any given radius. The small element, which subtends the angle 86 at the centre, is circulating round the centre in steady motion under the influence of the force due to the radial pressure gradient....
95 Exercises
Sketch the design of an algorithm mfree, which frees space and returns it to a map. 2. Section 9.1.2 states that the system locks a proccss being swapped so that no other process can swap it while the first operation is underway. What would happen if the system did not lock the process 3. Suppose the u area contains the segment tables and page tables for a process. How can the kernel swap the u area out 4. If the kernel stack is inside the u area, why can't a process swap itself out How would...
Heat Balance Of Marine Diesel Engine Drawing
Fig. 26-35 Two 12,500 kW Multi-Valve, Extraction, Non-Condensing Steam Turbine Generator Sets in University Application. Source Dresser-Rand Fig. 26-35 Two 12,500 kW Multi-Valve, Extraction, Non-Condensing Steam Turbine Generator Sets in University Application. Source Dresser-Rand Fig. 26-36 Multi-Valve 6,327 kW Condensing Steam Turbine Generator Set. Source Tuthill Corp. Murray Turbomachinery Div. Fig. 26-36 Multi-Valve 6,327 kW Condensing Steam Turbine Generator Set. Source Tuthill Corp....
Shaft Bossing and A Brackets
Twin-screw or multi-screw vessels have propeller shafts which leave the line of shell at some distance forward of the stern. To support the shaft overhang, bossings or 'A' brackets may be fitted. Bossings are a common feature on the larger multiple-screw passenger ships and are in effect a moulding of the shell which takes in the line of shaft for some distance. Access from inside the hull is thus provided to the shaft over a great proportion of its length, and it is afforded greater...
Thinners Mud Conditioning Agents
The substances discussed in this section have traditionally been called thinners. Thinners are added to mud to reduce flow resistance and gel development, and that was the original purpose in applying these materials. Experience has shown, however, that some of these so-called thinners perform other important functions, frequently of greater significance than improving the flow properties of the mud. Specifically, some of these substances are used to reduce filtration and cake thickness, to...
11 Integral body construction
The integral or unitary body structure of a car can be considered to be made in the form of three box compartments the middle and largest compartment stretching between the front and rear road wheel axles provides the passenger space, the extended front box built over and ahead of the front road wheels enclosing the engine and transmission units and the rear box behind the back axle providing boot space for luggage. These box compartments are constructed in the form of a framework of ties...
422 Block diagram manipulation
There are occasions when there is interaction between the control loops and, for the purpose of analysis, it becomes necessary to re-arrange the block diagram configuration. This can be undertaken using Block Diagram Transformation Theorems. Table 4.1 Block Diagram Transformation Theorems Table 4.1 Block Diagram Transformation Theorems Moving a summing point ahead of a block. Z GX Y Z X G Y G 4.9 A complete set of Block Diagram Transformation Theorems is given in Table 4.1. Example 4.3 Find the...
Operation of the rotary control valve and power piston
Neutral position (Fig. 9.16(a)) With no steering effort being applied when driving along a straight Fig. 9.16(a-d) Rack and pinion power assisted steering with rotary control valve Fig. 9.16(a-d) Rack and pinion power assisted steering with rotary control valve track, the longitudinal lands formed by the slots milled on the rotor periphery angularly align with the internal sleeve slots so that equal space exists between the edges of adjacent rotor and sleeve slots. Fluid therefore flows from...
How Compressor Packing Works
As previously described, a packing set consists of a series of sealing units. Compressor packing is not bottle-tight, but the amount of leakage is extremely small, a fraction of one percent of the capacity of the machine and usually within tolerable limits. In case of toxicity of the gas or danger of explosion or corrosion, leakage may be vented to a safe place. Because the individual rings will leak slightly, it is through the series of rings that the pressure is broken down from discharge to...
Spot Facing Operation
Another operation similar to counterboring is the spot-facing operation (Figure 4-29). Just enough metal is removed to provide a bearing surface for a washer, nut, or the head of a cap screw. The spot-facing tool should be mounted in the drill press spindle, and the pilot of the spot-facing tool should be aligned with the original drilled hole (Figure 4-30). Figure 4-24 Older type of motor reversing mechanism used for taps Vi inch to I inch in diameter. A magnetic reversing control, actuated by...
Evaporator Types And Applications
Evaporators may be classified as follows 1. Heating medium separated from evaporating liquid by tubular heating surfaces. 2. Heating medium confined by coils, jackets, double walls, flat plates, etc. 3. Heating medium brought into direct contact with evaporating liquid. By far the largest number of industrial evaporators employ tubular heating surfaces. Circulation of liquid past the heating surface may be induced by boiling or by mechanical means. In the latter case, boiling may or may not...
104fcc Part
The decade ofthe 1970's saw tremendous advances in digital electronics. In 1979 the FCC established rules for digital device radiated emissions for clock speeds greater than 9 kHz. For any digital devices that are marketed today (9 kHz is several orders of magnitude slower than today's devices), all such devices marketed must meet the FCC requirements for both conducted emissions and radiated emissions. Devices are classified according to their intended operating environment as either Class A...
1210 Through Plategirder Bridges With Floorbeams
For long or heavily loaded bridge spans, restrictions on depth of structural system imposed by vertical clearances under a bridge generally favor use of through construction. Through girders support the deck near their bottom flange. Such spans preferably should contain only two main girders, with the railway or roadway between them (Fig. 12.46). In contrast, deck girders support the deck on the top flange (Art. 12.8). The projection of the girders above the deck in through bridges may be...
The lantern ring
The lantern ring performs three basie functions 1. To supply new lubricant to the packing rings, which is normally lost in operation. 2. To supply 'back pressure', which aids in impeding the entrance of abrasive and corrosive material into the stuffing box. Abrasives and corrosives will damage the shaft or sleeve, and disintegrate the packing. 3. To cool the packing and shaft and dissipate the heat generated between these members, which will increase the normal service life of the packing and...
The generalised pressure drop correlation
The generalised pressure drop correlation by Eckert(62) has been developed as a practical aid to packed tower design and incorporates flowrates, physical properties of the fluid, a wide range of packings and pressure drop on one chart presented in dimensionally consistent form, as shown Figure 4.18. The broken line representing flooding lies above the top curve in Figure 4.18 and hence the correlation may be used with safety in design procedures. Most of the data on which it is based are...
Types Of Controls
In order to use an electric motor to drive a pump, a means of starting and stopping the motor is required. The devices used for this purpose can be called controls. Only small perhaps up to two or three hp (kW) motors can be controlled with a simple on-off switch (starting from full rated line voltage). This is because when a motor is first started it produces no back EMF and will draw very high starting currents. If the load inertia is very high, the motor can overheat during the long...
Bypass Systems TypesDesign Considerations
Continuous bypass systems As the title implies, continuous bypass systems provide continuous flow whenever the pump is running, regardless of the process demand. Figure 2 illustrates a simple system, with a bypass line branching off the pump discharge upstream of the main line check valve and containing a fixed orifice dimensioned by analysis to provide minimum required pump flow. The bypass line discharges into a reservoir that is at a lower pressure than the pump discharge. The bypass line...
2815 Voith Diwamatic transmission
This is shown in Fig. 28.23 and is an example of a 'split-torque' transmission, the engine power being transmitted partly by a single-stage torque converter and partly by direct mechanical action through an epicyclic gear. A forward and reverse gearbox of conventional form is also employed. The converter is somewhat different from the usual arrangement in that the impeller I discharges directly into the fixed casing R whose passages lead the fluid into the driven member D. The division of the...
Seals And Packing
AH machines that handle liquids or gases, such as pumps and compressors, must be sealed around their shafts to prevent fluid from leaking. To accomplish this, the machine design must include seals located at various points to prevent leakage between the shaft and housing. This chapter discusses sealing requirements and common seals. The two primary types of sealing devices used to seal around rotating shafts are packed-stuffing boxes and simple mechanical seals. A soft, pliable packing material...
An Inclined Manometer Is Used To Measure The Pressure Drop Between Two Taps
The three-fluid manometer illustrated in Fig. 4-P11 is used to measure a very small pressure difference P1 P2 . The cross-sectional area of each of the reservoirs is A, and that of the manometer legs is a. The three fluids have densities pa, pb, and pc, and the difference in elevation of the interfaces in the reservoir is x. Derive the equation that relates the manometer reading h to the pressure difference P1 P2. How would the relation be simplified if A a 12. A tank that is vented to the...
48Humber Super Snipe engine
The layout of this engine Figs 4.5 and 4.6 - like that of the Armstrong Siddeley Sapphire, Automobile Engineer, December 1953 - represented an intermediate stage in the trend of development from low to overhead camshaft. An interesting, but expensive, alternative is that of the Lea Francis 2.5-litre engine, Automobile Engineer, June 1952. Fig. 4.5 Humber Super Snipe engine - longitudinal section Fig. 4.5 Humber Super Snipe engine - longitudinal section Fig. 4.6 Humber Super Snipe engine -...
Electrodialysis Stack Design
Two different stack designs are used in large scale applications today. One is the so-called sheet flow and the other is the tortuous path flow design. A typical sheet flow electrodialysis stack is shown in Figure 4 Exploded view of an electrodialysis stack arrangement, indicating the individual cells and the sheet flow-type spacer, also containing the manifolds for distribution of different flow streams. Figure 4 Exploded view of an electrodialysis stack arrangement, indicating the individual...
Orbit Establishment
Several factors are involved in reaching the desired orbit, including establishing the correct burn-out conditions, staging, launch timing, launch pad location, and launch direction. Figure 3-6 depicts a typical launch situation from the U.S. launch site at the Kennedy Space Center (KSC) in Florida. Burn-out Conditions. The launch vehicle both accelerates and raises the payload from the surface of the earth along a predetermined launch path (trajectory). The launch path must intersect the...
Stress Concentrations
The basic stress quantities used in design assume a constant or gradual change in cross-section. The presence of holes, shoulder fillets, notches, grooves, keyways, splines, threads, and other discontinuities cause locally high stresses in structural members. Stress concentration factors associated with the aforementioned changes in geometry have been evaluated mathematically and experimentally with tools such as finite element models and photoelastic studies, respectively. The ratio of true...
Induced Gas Flotation IGF
In the induced gas flotation IGF or IAF process, which resembles the design of a subaeration minerals flotation cell see Figure 2 , bubbles are induced mechanically. IGF uses a star-shaped impeller to generate intense local turbulence. This results in subatmospheric pressures being generated in the region surrounding the impeller which causes gas to be induced from the gas space at the top of the compartment via gas inlet Figure 1 Flow diagram for a dissolved air flotation system. Courtesy of...
87 Wheel balancing
The wheel and tyre functions are the means to support, propel and steer the vehicle forward and backward when rolling over the road surface. In addition the tyre cushions the wheel and axle from all the shock impacts caused by the roughness of the road contour. For the wheel and tyre assembly to rotate smoothly and not to generate its own vibrations, the wheel assembly must be in a state of rotatory balance. An imbalance of the mass distribution around the wheel may be caused by a number of...
Metering Or Proportioning
Conventional reciprocating pumps can be adapted to function as metering or proportioning devices in the transfer of liquids. The principal adaptation is the addition of a means of varying the pumping rate and predicting what that rate will be, which makes the modified units suitable for use as final control elements in continuous-flow processes. Metering pumps are often employed where two or more liquids must be proportioned or where mixture ratios must be controlled. These effects are achieved...
The Drilling Choke
Outboard of the gate valves are the drilling chokes. The drilling choke is the heart of the well control operation. Well control was not routinely possible prior to the advent of the modern drilling choke. Positive chokes and production chokes were not designed for well control operations and are not tough enough for well control operations. Production chokes and positive chokes should not be included in the choke manifold unless there is a specific production-well testing requirement. Under...
Prevention And Mitigation Of Nonpoint Source Pollution
There has been a growing emphasis on prevention and mitigation of nonpoint source pollution during the past decade. Many counties now require agricultural farm plans that provide site-specific guidance for minimizing agricultural nonpoint source pollution. Similarly, many cities are now required to have discharge permits for storm drains that empty into natural water bodies. The following section will describe current practices for preventing and mitigating nonpoint source pollution from three...
Construction Details
Component Parts The main components of a single-stage steam turbine are shown in Figure 1. FIGURE 1 Component parts of steam turbines (Elliott) FIGURE 1 Component parts of steam turbines (Elliott) Function and Operation Single-Stage Turbine The steam chest and the casing contain the steam furnished to the turbine, being connected to the higher-pressure steam supply line and the lower-pressure steam exhaust line, respectively. The steam chest, which is connected to the casing, houses the...
552 Backing bars and backing strips
Although it is possible to deposit a sealing run on the reverse side of a butt weld without a back-gouge, this cannot be relied upon to give a sound, defect-free weld. Single sided joints may be welded by TIG to produce a sound root pass but the conventional (non-pulsed) MIG process often requires either permanent or temporary backing on which to deposit the MIG root pass. The purpose of the backing bar or strip is to support the root pass where conditions make the control of the bead...
Xanthan Gum XC Polymer
Xanthan gum is properly classed with the natural polymers, although it is actually obtained in its produced rather than in its natural form. Xanthan gum production method was developed at the Northern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Peoria, Illinois, in 1961. Jeanes et al129 present a recent review containing 49 references on xanthan. Xanthan is a water-soluble polysaccharide produced by bacterial action (genus Xanthomonas) on...
14 Parallel Manipulators
Robotic manipulators first appeared as mechanical systems constituted by a structure consisting of very robust links coupled by either rotational or translating joints, the former being called revolutes, the latter prismatic joints. Moreover, these structures are a concatenation of links, thereby forming an open kinematic chain, with each link coupled to a predecessor and a successor, except for the two end links, which are coupled only to either a predecessor or to a successor, but not to...
The Hydrologic Cycle And Water Availability
The hydrologic cycle is a useful starting point for the study of water supply. This cycle, illustrated in Fig. 6-1, includes precipitation of water from clouds, infiltration into the ground or runoff into surface water, followed by evaporation and transpiration of the water back into the atmosphere. The rates of precipitation and evaporation transpiration help define the baseline quantity of water available for human consumption. Precipitation is the term applied to all forms of moisture...
Wettedwall Columns
Wetted-wall or falling-film columns have found application in masstransfer problems when high-heat-transfer-rate requirements are concomitant with the absorption process. Large areas of open surface are available for heat transfer for a given rate of mass transfer in this type of equipment because of the low mass-transfer rate inherent in wetted-wall equipment. In addition, this type of equipment lends itself to annular-type cooling devices. Gilliland and Sherwood Ind. Eng. Chem., 26, 516 1934...
31 Creeprecovery Testing
If a constant static load is applied to a sample, for example, a 5-lb weight is put on top of a gallon milk container, the material will obviously distort. After an initial change, the material will reach a constant rate of change that can be plotted against time (Figure 3.2). This is actually how a lot of creep tests are done, and it is still common to find polymer manufacturers with a room full of parts under load that are being watched. This checks not only the polymer but also the design of...
Moments of statical stability
When a ship is inclined by an external force, such as wind and wave action, the centre of buoyancy moves out to the low side, parallel to the shift of the centre of gravity of the immersed and emerged wedges, to the new centre of gravity of the under-water volume. The force of buoyancy is considered to act vertically upwards through the centre of buoyancy, whilst the weight of the ship is considered to act vertically downwards through the centre of gravity. These two equal and opposite forces...
45Kort nozzles
The Kort nozzle is a fixed annular forward-extending duct around the propeller. The propeller operates with a small gap between blade tips and nozzle internal wall, roughly at the narrowest point. The nozzle ring has a cross-section shaped as a hydrofoil or similar section. The basic principle underlying nozzle operation is most simply explained according to Horn (1940) by applying simple momentum theory to the basic law of propulsion. This postulates that, for generation of thrust with good...
Chemical Control of Phosphating Processes
An efficiently operated phosphating line includes close chemical control of all materials used. Even the mineral content of plain water rinses may need to be controlled to avoid leaving a residue on parts. To obtain satisfactory phosphate coatings on steel surfaces, phosphating solutions must be chemically controlled within limits. These limits vary, depending on the specific phosphating concentrate used. Solutions should be tested on a regular schedule. Frequency of tests is determined by the...
Sealing of Anodic Coatings
When properly done, sealing in boiling deionized water for 15 to 30 min partially converts the as-anodized alumina of an anodic coating to an aluminum monohydroxide known as Boehmite. It is also common practice to seal in hot aqueous solution containing nickel acetate. Precipitation of nickel hydroxide helps in plugging the pores. The corrosion resistance of anodized aluminum depends largely on the effectiveness of the sealing operation. Sealing will be ineffective, however, unless the anodic...
General Methods of Metal Powder Production
Metal powders are produced by mechanical methods or chemical methods. The commonly used methods include water and gas atomization, milling, mechanical alloying, electrolysis, and chemical methods including reduction of oxides. Suitable methods for powder production depend on required production rates, powder properties, and the physical and chemical properties of the material. Chemical and electrolytic methods are useful for producing high-purity powders. Mechanical comminution (or milling) is...
Coldstream Impact Process
The Coldstream process is a high-velocity process in which material is entrained in a gas stream and projected against a stationary target. After material has struck the target and shattered, it is removed from the impact chamber by suction. Material is then transported to a classifier, which allows oversized products to drop into a storage vessel for subsequent impact against the target. The finished product is separated by the classifier and transported to collection containers. The process...
Production Sintering Practices Sintering of Nickel and Nickel Alloys
Sintered nickel-base materials enjoy wide commercial usage due to their unique properties, such as corrosion resistance, wear resistance, mechanical strength at low and elevated temperatures, thermal expansion, electrical conductivity, and magnetic permeability. Commercial products represent a wide range of shapes, sizes, and microstructures. Sintered products with S 90 porosity are technologically as important as fully dense products. Sintering practices aimed at achieving such diverse...
The Principle of Electrodialysis
The principle of electrodialysis is illustrated in Figure 1. A typical electrodialysis cell arrangement consists of a series of anion and cation exchange membranes arranged in an alternating pattern between an anode and a cathode to form individual cells. If an electrolyte solution is passed through these cells and an electrical potential is established between the electrodes, the positively charged cations migrate towards the cathode and the negatively charged anions towards the anode. The...
Post Column Apparatus
If post-column modification of the mobile phase or analyte is required, then the system will have a post-column apparatus in the flow path. Modification of the mobile phase (e.g. addition of buffers, changing the pH, and solvent strength) may be needed to enhance the compatibility of the mobile phase with the detector, while post-column derivatization of the analyte may be needed to improve the detection properties of the analytes after their separation. In either case, a post-column addition...
Mechanical Cleaning and Finishing
Mechanical cleaning and finishing methods most commonly employed for processing iron castings include abrasive blast cleaning (the most commonly used method for cleaning cast irons), abrasive waterjet cleaning and finishing, vibratory finishing, barrel finishing, and shot peening. Blast cleaning of castings is a process in which abrasive particles are propelled at high velocity to impact the casting surface and thereby forcefully remove surface contaminants. The contaminants are usually...
232 Use of the triboelectric series
As has already been noted, the separation of electrostatic charges depends, primarily, on the difference in the work functions of the materials involved. The greater the difference, the larger is the charge separated and vice versa. On this basis it should be expected that to reduce static charging materials should be selected which differ as little as possible in their work functions. Indeed, the contact electrification between identical materials should be zero. Coehn 3 put forward a rule,...
Chromate Conversion Coatings
The corrosion of cadmium plate can be retarded by applying a supplemental chemical conversion coating of the chromate type. The chromate films are produced by immersing the plated article in a solution containing chromic acid or other chromates and catalytic agents. These films provide protection against initial corrosion through the inhibitive properties of the water-soluble chromium compounds present. However, the chromate finish must not be applied before stress relieving or baking, because...
Surface Preparation for Electroplating
Preparation for plating is one of the most critical of all cleaning operations, because maximum adhesion of the plated coating to the substrate is the major requirement for quality work. Maximum adhesion depends on both the elimination of surface contaminants in order to induce a metallurgical bond whenever possible and the generation of a completely active surface to initiate plating on all areas. In addition to pickling or other descaling operations, adequate cleaning requires multistage...
Cargo Pumps And Associated Pumps
Cargo pumps are used to discharge the liquid cargo transported in a vessel's tanks. The types of vessels that carry liquid bulk cargo include ultra-large and very-large crude carriers (ULCC's and VLCC's), multi-petroleum product and chemical carriers, and liquefied natural gas (LNG) and liquefied petroleum gas (LPG) carriers. In addition, some freighters and supply vessels have tanks in which they can carry a limited amount of liquid cargo. As liquid cargo is discharged from a vessel, the level...
Wearing Rings
Wearing rings provide an easily and economically renewable leakage joint between the impeller and the casing. A leakage joint without renewable parts is illustrated in Figure 39. To restore the original clearances of such a joint after wear occurs, the user must either (1) build up the worn surfaces by welding or metal spraying, or (2) buy new parts. The new parts are not very costly in small pumps, especially if the stationary casing element is a simple suction cover. This is not true for...
2710 Basic principle of the Wilson gearbox
A Wilson type gearbox is illustrated in Fig. 27.8(a), and the functioning of its various secondary trains is shown in (b) to f). The primary epicyclic gear train is common to all the ratios. Its sun S1, Fig. 27.8(b), is driven by shaft D, which is coupled directly to the engine crankshaft, while its planet carrier C1 is coupled directly to the transmission line to the road wheels. In other words, these two elements are respectively the input and output regardless of ratio selected. The required...
4018Reversible and irreversible steering
With most steering gears, if the road wheels are gripped, they can be swung about their kingpins, causing the steering wheel inside the car to rotate. If however, the friction forces within the steering gear are high enough to prevent this, the gear is said to be irreversible. In general, the higher the steering ratio, the greater is the tendency to irreversibility, since a high ratio helps the driver to overcome the frictional resistance when he uses the steering wheel but multiplies that...
Bow thruster
The bow thruster is a propulsion device fitted to certain types of ships to improve manoeuvrability. The thrust unit consists of a propeller mounted in an athwartships tunnel and provided with some auxiliary drive such as an electric or hydraulic motor. During operation water is forced through the tunnel to push the ship sideways either to port or starboard as required. The unit is normally bridge controlled and is most effective when the vessel is stationary. A controllable-pitch type thruster...