THE OPTIMALITY OF THE “CUT ACROSS THE BOARD” RULE APPLIED TO AN INVENTORY MODEL

A common procedure in budget allocation is to let the different entities of an organization determine their optimal budgets. Once the individual requests are received, they are then cut by a common factor, as necessary, so that a global constraint is satisfied. We refer to this procedure as the “cut across the board” rule. In general, this method will not result in a globally optimal solution. In this paper we identify conditions that assure the global optimality of die “cut (or expand) across the board” rule. We specifically focus on a constrained multi-item inventory model and generalize results of Rosenblatt [10] and Plossl and Wight [8]. In addition, we briefly discuss applicability of the results to other areas.     

The tradeoff between sampling and switching: New sequential procedures for indifference-zone selection

Statistical Ranking and Selection (R&S) is a collection of experiment design and analysis techniques for selecting the “population” with the largest or smallest mean performance from among a finite set of alternatives. R&S procedures have received considerable research attention in the stochastic simulation community, and they have been incorporated in commercial simulation software. One of the ways that R&S procedures are evaluated and compared is via the expected number of samples (often replications) that must be generated to reach a decision. In this paper we argue that sampling cost alone does not adequately characterize the efficiency of ranking-and-selection procedures, and the cost of switching among the simulations of the alternative systems should also be considered. We introduce two new, adaptive procedures, the minimum switching sequential procedure and the multi-stage sequential procedure with tradeoff, that provide the same statistical guarantees as existing procedures and significantly reduce the expected total computational cost of application, especially when applied to favorable configurations of the competing means.     

Validation and calibration of a lateral confinement model for long-rod penetration at ordnance and high velocities

In designing targets for laboratory long-rod penetration tests, the question of lateral confinement often arises, “How wide should the target be to exert enough confinement?” For ceramic targets, the problem is enhanced as ceramics are usually weak in tension and therefore have less self-confinement capability. At high velocities the problem is enhanced even more as the crater radius and the extent of the plastic zone around it are larger. Recently we used the quasistatic cavity expansion model to estimate the resistance of ceramic targets and its dependence on impact velocity [1]. We validated the model by comparing it to computer simulations in which we used the same strength model. Here we use the same approach to address the problem of lateral confinement.

We solved the quasistatic cavity expansion problem in a cylinder with a finite outside radius “b” at which σ_r (b) = 0 (σ_r = radial stress component). We did this for three cases: ceramic targets, metal targets, and ceramic targets confined in a metal casing. Generally, σ_r (a) is a decreasing function of “a” (“a” = expanding cavity radius, and σ_r (a) = the stress needed to continue opening the cavity). In the usual cavity expansion problem b → ∞, σ_r (a) = const., R =−σ_r (a) (R = resistance to penetration). For finite “b” we estimate R by averaging σ_r (a) over a range o ≤ a ≤ a_r, (where a_r, the upper bound of the range, is calibrated from computer simulations).

We ran 14 computer simulations with the CTH wavecode and used the results to calibrate a_r for the different cases and to establish the overall validity of our approach.

We show that generally for D_t/D_p > 30, the degree of confinement is higher than 95% (D_t = target diameter; D_p = projectile diameter; and degree of CONFINEMENT = R/R_∞; R∞ = resistance of a laterally infinite target). We also show the tensile strength of ceramic targets (represented by the spall strength P_min) has a significant effect on the degree of confinement, while other material parameters have only a minor effect.     

Optimal parallel funding of research and development projects

To insure against the costs of failure, research managers often initiate several more-or-less independent research projects with the same target. But then they face the problem of how many parallel ”teams“ to fund in order to maximize the probability of a timely breakthrough. If there are too many teams, resources are stretched too thin, but if there are too few teams, an opportunity for exceptional achievement may be missed. Several possible project objectives are identified, including maximizing the achievement of the best team and maximizing the probability that at least one team will attain a threshold. General optimization problems based on these goals are then formulated in fixed, uncertain, and competitive environments. These problems are solved analytically and numerically for achievement distributions in a family based on the exponential distribution. The applicability of these solutions to funding R&D, and to other problems such as supporting athletes, is then discussed.     

The External Sourcing of Technological Knowledge by US Pharmaceutical Companies: Strategic Goals and Inter-organizational Relationships

This study of the organization of the discovery function by large US pharmaceutical companies (LPCs) examines an important knowledge acquisition strategy—external sourcing of compounds and technologies. Through a critical examination of the “capabilities” thesis in strategic management and of the theoretical conceptualization in organization studies of innovation networks, we undertake an in-depth qualitative analysis of the network relationships LPCs establish with biotechnology firms/public research laboratories. We additionally examine the motivations and degree of strategic intent of R&D managers involved in external knowledge sourcing. The paper identifies the tensions and contradictions in network relationships and indicates how these lead to changes in knowledge sourcing. This qualitative analysis is placed in its industry and technology context. This reveals both the pressures towards and the trends in external knowledge sourcing, as compared with in-house discovery. Extensive interviews with US LPCs and biotechnology firms provide a rare glimpse of how some of the most important actors in global innovation networks handle a significant new innovation strategy.     

A study on in vitro release of five brands of phenytoin capsules, marketed in iran

In relation to the new pharmaceutical system in Iran, the in vitro release of five brands of 100 mg phenytoin sodium capsules, namely A,B,C,D & E were determined in distilled water. using three dissolution methods, i.e. Rotating basket, Magnetic basket and Levy beaker method. Also the average amount of phenytoin content of each brand was measured.

The results showed that although the dissolution rate of each product is different by each method, but the pattern of drug release is more or less similar.

The dissolution time for products C and D is much longer than those of products A,B & C with all methods, but the dissolution behaviour of capsules C & D is not equivalent to those of standard “slow release” phenytoin capsules. The release pattern of products A & E are similar to those of standard “fast release” phenytoin capsules. The dissolution of product B is poor and not acceptable.     

A Relational Approach to Organization Design

The paper criticizes the currently dominant view of organization forms as “discrete alternatives” and “coherent” set attributes, and proposes a more refined and micro-analytic view of organization forms as particular combinations of coordination mechanisms and rights allocations. This view is relevant for understanding and devising “new” forms and proposing solutions for governing the composite and fast changing systems of today. The view is “relational” as it offers a procedure for devising “superior” configurations as combinations—relations between organizational components—in a quasi-continuous space of possibilities. The approach is sustained by the quantitative methods of network analysis as applied to relations among firm's resources and activities. Theoretically, the approach revisits organization design, integrating classic organization theory tenets with the new inputs provided by organizational economics. Substantively, it is argued that a mix of much differentiated coordination mechanisms is usually superior to the codified, “packaged”, allegedly “coherent”, forms of organization. The procedure presented in the paper is applied to a field experiment in a medium size firm.1     

Commodity Supply Allocation with Linear Costs Recognizing Linear Quality Premium/Penalty Payments

The article demonstrates that, where premium/penalty payments as a function of quality characteristics and customer apply to commodities provided by a supplier from alternative locations to alternative customers, the use of linear programming for “optimal” allocation without specifically recognizing premium/penalty payments in the L.P. model may substantially sub-optimize overall allocation profit opportunities. A numerical example for a commodity with two different quality characteristics having different premium/payment structures is given to illustrate this fact. Also, administrative considerations which must be addressed to successfully implement the approach are identified.     

The Effect of the Coefficient of Variation of Operation Times on the Allocation of Storage Space in Production Line Systems

This paper studies the effect of the coefficient of variation of operation times on the optimal allocation of storage space in production line systems. The operation times at each station are modelled by a two-stage Coxian distribution. This work extends the results of our previous study of the storage allocation problem with exponentially distributed operation times. Interpreting Stage 1 of the two-stage Coxian distribution as the normal service for an item at a station and Stage 2 as down time at the station, our model can also be used to study the effect of breakdowns on the allocation of storage space in production line systems. The results show that the “bowl effect” whereby the center stations should be given preferential treatment becomes more pronounced with higher variability in the operation times. Another general conclusion is that the overall optimal storage allocation commonly follows a “storage bowl phenomenon” whereby the allocation of buffer storage space fits an inverted bowl pattern when the total storage space is also a decision variable     

Attitudes of commercial motor vehicle drivers towards safety belts

Despite the fact that Hawaii has one of the highest seat belt use rates for passenger vehicles in the United States, and has had a mandatory seat belt use law since the 1980s, studies have shown that commercial motor vehicles (CMV) seat belt use rates are low. To better understand this phenomenon, a comprehensive survey of commercial vehicle drivers was conducted in Hawaii to ascertain attitudes and self-reported behaviors regarding seat belt use. A total of 791 drivers responded to a written questionnaire implemented at weigh stations and distributed to various trucking firms and transport centers. Approximately 67% reported that they use seat belts “always” when driving a CMV (commercial motor vehicle), yet when asked how often do other CMV drivers use seat belts, only 31% responded “always.” Interestingly, 86% of these same drivers reported that they use seat belts “always” when driving a personal vehicle. The major reason cited for non-use of belts was “frequent stops/inconvenience” (29%), and “not safety conscious” (23%). Notably, the self-reported use of safety belts is highest among operators of vans (88% said “always”), followed by buses (87% said “always”) and lowest among truck drivers (only 60% said “always”). In this paper, some of the differences between self-reported users and non-users are explored and a multivariate logit model was developed to predict the odds of belt use as a function of various factors.     

A dynamic measure of order in structural glasses

Although some patterns of physical behavior are common in the glass transition and in the properties of supercooled liquids and glasses (characteristic viscoelasticity, temperature dependence of viscosity and relaxation times, property evolution through “physical aging”, difficulties in performing equilibrium measurements or simulations, etc.), it is difficult to arrive at a definition of the glass transition which distinguishes it from other phenomena exhibiting similar features. The present paper addresses this problem by defining a dynamical measure of order involving the average “shape” of particle trajectories in supercooled liquids. This dynamic order parameter should provide a measure of “closeness” to the glass transition and some indirect insights into the physical nature of supercooled liquids and glasses. Arguments are given that the proposed dynamic measure of order [“generalized capacity”, C(T)] is related to the temperature-dependent “effective hydrodynamic radius” R_H(T) measured in supercooled liquids and model numerical calculations are given to support this view. Some consequences of the intermittent particle motion at low temperatures for stress relaxation are also discussed.     

On new types of non-crystalline metallic composite

The structure and mechanical properties of new types of non-crystalline metallic composites, namely “glass-quasi-crystal”, “glass-disclinated nanocrystal” and “quasi-crystal(-glass)-disclinated nanocrystal” composites are theoretically examined. In particular, a theoretical model is proposed which effectively describes the relationship between plastic deformation and the growth of the glassy phase in metallic “glass-quasi-crystal” composite materials. Here also basic features of both the structure and the mechanical properties of the “glass-disclinated nanocrystal” and “quasi-crystal(-glass)-disclinated nanocrystal” composites are theoretically examined. It is shown that such composites are characterized by a very high yield stress.     

A Flow-Through Dissolution Approach to In Vivo/In Vitro Correlation of Adinazolam Release from Sustained Release Formulations

A Copley^TM fraction collector and a Disotest^TM flow-through system were coupled to provide an automatic discrete sampling flow-through dissolution system for use both in the “open-loop” and “closed-loop” mode. The system was used to investigate the release characteristics of adinazolam in sustained release formulations using a pH 1.2 simulated gastric fluid (without enzymes) dissolution medium (USP XXI). These experimental formulations are designed to provide relatively slow to rapid drug release. The dissolution effluent was analysed off-line by reverse phase HPLC to determine the adinazolam concentration at programmed timed intervals. The differential dissolution profiles produced when the system is used in the “open-loop” configuration are more discriminating in describing the release characteristics of the formulations according to the relative release rates than the “closed-loop” cumulative profiles. Using the characteristic dissolution time parameter from the Weibull function, a better correlation with in vivo bioavailability data was achieved for the data from the system in the “open-loop” mode than when it was used in the “closed-loop” mode. In the “open-loop” mode the Weibull function characteristic dissolution time parameter yielded the best quantitative correlation with a correlation coefficient of 0.92 compared to a value of 0.85 for the “closed-loop” configuration     

When Does a National Innovation System Start to Exhibit Systemic Behavior?

Despite the diversity of national profiles, the relationship between R&D structure and industrial structure, amongst others, is considered a crucial determinant of a country's national innovation system (NIS). This paper aims at investigating the systematic relationship between the two structures with respect to the portfolio of resource allocation. By proposing some operational definitions of R&D structure and industrial structure, a comparative analysis is conducted for the national profiles of OECD member economies. The correlation analysis reveals that, in an overall sense, there exists significant correlation between the two structures and the degree of correlation has increased over time, indicating that the linkage between innovation policy and industrial policy has become closer. Most interestingly, it is found that there may exist a threshold value of national R&D investment to GDP, around 2 percent, that makes the correlation between R&D structure and industrial structure significant. This threshold is the time point when R&D starts to exercise systematic effects on industrial structure and thus NIS starts to behave like a system.     

A “Six Sigma”© Black Belt Case Study: G.E.P. Box's Paper Helicopter Experiment Part A

This article presents an application of the “Six Sigma” DMAIC model to G.E.P. Box's famous “paper helicopter” experiment. The define, measure, and analyze phases are presented here, and the improve and control phases are presented in a follow-up article. The intent of this article is to present the reader with a case study for structuring a “Six Sigma” Black Belt project.     

Quality assurance and staff training

“G.M.P. Trends” is an american magazine publishing extracts of inspection reports: It is an official statement of errors, faults, omissions observed in the US pharmaceutical industry as regard good manufacturing pratices. A comparison between the “G.M.P. Trends” and the (“BPF”) “Bonnes Pratiques de Fabrication” (Good manufacturing pratices) points out the errors, defects or omissions observed and thus enable t o remodel staff training (1) (2).

Staff training is dealt with different chapters of the “BPF” staff, documents, samples, computerisation and risk generating product. Staff training is regarded as a mean for action: objectives, priority aims, choices and exchanges are to be defined.

We intend t o develop an example of answer to staff training needed in the pharmaceutical industry. The aim of this answer is the implementation of the good manufacturing pratices in a system which guarantees quality. This training is carried out within the framework of the directives and recommandations of the W.H.O. and U.N.I.D.O. with as a target the manufacturing of tablets of essential drugs.     

A “Six Sigma”© Case Study: G.E.P. Box's Paper Helicopter Experiment—Part B

This article presents an application of the “Six Sigma” DMAIC model to G.E.P. Box's famous “paper helicopter” experiment. The Improve and Control Phases are presented here. The Define, Measure, and Analyze Phases were presented in an earlier paper. The intent of this article is to present the reader with a case study for structuring a “Six Sigma” project.     

Critical velocity for rails in hypervelocity launchers

This paper is related to the dynamic and strength analysis and optimized design of hypervelocity electromagnetic launchers. Projectile motion along the rails at critical velocity is associated with damaging resonant regimes. These regimes reveal increased displacements and stress that can lead to failure of a launcher. To calculate critical velocity and to visualize dynamic deformations of the launcher we have developed two alternative approaches utilizing analytical and finite element models. The first approach employs a closed form analytical solution for critical velocity that is based on the Bernoulli–Euler model of a beam resting on an elastic foundation and subjected to a moving load. The critical velocity is expressed as a function of geometric and material parameters of the rail and equivalent stiffness of the supporting structure. The stiffness of the supporting structure is found from a 2D finite element model. In the second approach, we employed beam finite element and 3D solid finite element models to visualize and measure the “natural” and “forced” bending waves traveling along the rails. These approaches helped to better understand the transient resonant dynamic processes and offered insight on how to alter the launching device materials and geometry to reduce the critical-velocity effects.     

A new analytical model about the relationship between nominal failure stresses and porosity for foamed metals under biaxial tension

Foamed metals have been widely used as various engineering materials, and their mechanical properties have also been drawing extensive attention. In the present paper, a new mechanical and analytical model is established for these materials with isotropic three-dimensional reticulated structure under biaxial tension, and the mathematical equation about biaxial nominal stresses is deduced for the biaxial tension at the beginning of failure of the porous body. With the relevant experiment, the relation formula is proved to be very effective. Different from the relevant theoretical system of Gibson and Ashby, the present mathematical relationship can be conveniently achieved from directly using the “beam theory” on this mechanical and analytical model. In addition, this relationship can be further expressed as the mathematical relationship among the nominal failure “deviatoric stress”, the nominal failure “average stress” and porosity, but the concepts of both the “deviatoric stress” and the “average stress” can appear just from the mathematical treatment.     

Guides “bimorphes” d''ondes ultrasoniques “bimorph” ultrasonic wave guides”

An analysis of the dispersion of elastic waves is presented for two types of long ultrasonics wave-guides that we qualify of “bimorph”: (i) a “three-layer” guide made of two different materials and (ii) a “clad core” guide built up of a rectangular core surrounded by a cladding, the materials of the rod and cladding having different properties. An analytical model is proposed to describe the extensional, flexural and torsional motions in “bimorph” wave guides having two geometrical and material symmetry axes. The asymptotic behaviour of the model allows one to select the material properties which lead to modes guided essentially either in the central layer or in the core of the bimorph guide. Moreover, the dispersive properties of a “bimorph” can be controlled through the choice of geometrical and material parameters.