Design requirement

The following design requirements for system size, workspace, precision and forces have been developed in collaboration with doctors and researchers at Brigham and Women s Hospital in Boston, Massachusetts, USA. 

Binary systems have discrete workspaces consisting in aU possible end-effector locations. Here, precision is defined as the minimum distance between a random point in the required workspace from the closest possible needle tip location. Manual needle insertion methods currently in use have a perforated template with holes 5 mm apart to guide the needle. 

Tests were performed on beef muscle to establish the magnitude of the external forces applied on the needle during insertion [24]. Beef muscle has similar properties to those of the tissue between the perineum and the prostate. In these tests, forces are considered to be applied at the needle s point of entry. Combining these results with those of the literature give a maximum axial force of 14 N and a maximum radial force of 1.6 N for a beveled needle tip [25]. A trihedral needle tip would lower the axial force to -8.25 N and the radial force to -0.5 N. Hence, trihedral needles are desirable. 

The design of structures of this type involves some very unusual geotechnical problems. The requirements that gravity structures should be designed to meet are the following. 

When subjected to maximum wave and wind loads the structure shall have an acceptable factor of safety against horizontal sliding and against a shear failure in the foundation soil. 

The displacements experienced by the gravity structure should be acceptable when subjected to maximum wave and wind forces. 

The factor of safety against a shear failure and the displacements should also be acceptable after the structure has been subjected to periods of repeated wave forces in severe storms. 

The natural frequencies of the structure should differ from those of wave forces, ensuring that there will be no resonance. 

A corrosion monitoring philosophy should be estabhshed based upon a detailed review of the process conditions and plant materials. The potential corrosion problems arising from both routine and nonroutine operation of the plant should be assessed in order to determine areas that may be affected. The actual process streams to be monitored and the monitoring devices to be used should be based 

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However, care should be taken not to ignore practical constraints when setting To achieve a small ATmi in a design requires... 

The simulation (Lu et al., 1998) suggested how Ig domains achieve their chief design requirement of bursting one by one when subjected to external forces. At small extensions, the hydrogen bonds between strands A and B and between strands A and G prevent significant extension of a domain, i.e.. 

NAMD [7] was born of frustration with the maintainability of previous locally developed parallel molecular dynamics codes. The primary goal of being able to hand the program down to the next generation of developers is reflected in the acronym NAMD Not (just) Another Molecular Dynamics code. Specific design requirements for NAMD were to run in parallel on the group s then recently purchased workstation cluster [8] and to use the fast multipole algorithm [9] for efficient full electrostatics evaluation as implemented in DPMTA [10]. 

Control technology requirements vary according to the scale of operation and type of emission problem. For instance, electrostatic precipitator design requirements for fly-ash control from 1000-MW coal-fired power boilers differ from those for a chemical process operation. In the discussion that follows, priority is given to control technology for the CPI as opposed to the somewhat special needs of other industries. 

Recent advances in Eischer-Tropsch technology at Sasol include the demonstration of the slurry-bed Eischer-Tropsch process and the new generation Sasol Advanced Synthol (SAS) Reactor, which is a classical fluidized-bed reactor design. The slurry-bed reactor is considered a superior alternative to the Arge tubular fixed-bed reactor. Commercial implementation of a slurry-bed design requires development of efficient catalyst separation techniques. Sasol has developed proprietary technology that provides satisfactory separation of wax and soHd catalyst, and a commercial-scale reactor is being commissioned in the first half of 1993. 

Quality Function Deployment. Sometimes referred to as the House of Quahty, quahty function deployment (QFD) is a technique for translating the voice of the customer iato design requirements (19). This is a systematic approach identifyiag customer expectations and relating the expectations to product properties. The usage of QFD ia the chemical iadustry appears to be growing. QFD results ia chemical specifications optimized to assure the material is suitable for its iatended use and performs up to customer expectations. 

Some design factors, however, work against composites. For example, glass fiber-reinforced plastics generally have lower modulus (stiffness) than metals. Thickness and shape adjustments are requited where stiffness is a critical design requirement. With appropriate reinforcement, any modulus, even greater than that of metals, can be achieved. However, it may become expensive and uneconomical to do so. 

Catalytic oxidation systems are normally designed for destmction efficiencies that range from 90 to 98% (27). In the early 1980s, typical design requirements were for 90% or higher VOC conversions. More recently, however, an increasing number of appHcations require 95 to 98% conversions to meet the more stringent emission standards (20). 

The code provides design requirements for closures which are flat, elhpsoidal, spherically dished, hemispherical, conical (without transition knuckles), conic convex to pressure, toriconical concave to pressure, and toriconical convex to pressure. 

Design requirements. A slightly higher level of design expertise is required for electric tracing than for steam tracing. 

Packed Columns versus Plate Columns Packed columns are usually specified when plate devices would not be feasible because of undesirable fluid charac teristics or some special design requirement. Conditions favoring packed columns are ... 

It is seldom possible to specify an initial mixer design requirement for an absolute bubble size prediction, particularly if coalescence and dispersion are involved. However, if data are available on the actual system, then many of these correlations could be used to predict relative changes in drop size conditions with changes in fluid properties or impeller variables. 

The membranes are supported and kept apart by feed spacers. A typical cell gap is 0.5-2 mm. The spacer also helps control solution distribution and enhances mass transfer to the membrane. Given that an industrial stack may have up to 500 cell pairs, assuring uniform flow distribution is a major design requirement. 

Economics It is ironic that a great virtue of membranes, their versatility, makes economic optimization of a membrane process veiy difficult. Designs can be tailored to veiy specific applications, but each design requires a sophisticated computer program to optimize its costs. Spillman [in Noble and Stern (eds)., op. cit., pp. 589-667] provides an overall review and numerous specific examples including circa 1989 economics. 

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