Qualitative Ordinal Scales: The Concept of Ordinal Range

Many practical problems of quality control involve the use of ordinal scales. Questionnaires planned to collect judgments on qualitative or linguistic scales, whose levels are terms such as “good,” “bad,” “medium,” etc., are extensively used both in evaluating service quality and in visual controls for manufacturing industry. In an ordinal environment, the concept of distance between two generic levels of the same scale is not defined. Therefore, a population (universe) of judgments cannot be described using “traditional” statistical distributions since they are based on the notion of distance. The concept of “distribution shape” cannot be defined as well. In this article, we introduce a new statistical entity, the so-called ordinal distribution, to describe a population of judgments expressed on an ordinal scale. We also discuss which of the traditional location and dispersion measures can be used in this context and we briefly analyze some of their properties. A new dispersion measure, the ordinal range, as an extension of the cardinal range to ordinal scales, is then proposed. A practical application in the field of quality is developed throughout the article.     

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 “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.     

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.     

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     

A fast procedure for computing the total system cost of an appointment schedule for medical and kindred facilities

Scheduling outpatients and medical operation rooms has the following structure: Nusers are given appointment times to use a facility, the duration required by the facility to service each user is stochastic. The system incurs a “user idle cost” if a user arriving at the appointed time finds the facility still engaged by preceding users, while a “facility idle cost” is incurred if the facility becomes free before the next user arrives. We develop an accurate procedure to compute the expected total system costs for any given appointment schedule. Compared to earlier related procedures, ours is much faster and can handle larger problems as well as very general service-time distributions. We then show that this fast computation procedure enables one to determine easily the “lowest-cost appointment schedule” for any given “job” (i.e., “user”) sequence. This in turn will enable one to search for the optimal job sequence that has the best “lowest-cost appointment schedule”.     

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.     

Addition of “Living” Polymers onto C60.

Various “living” polymers were grafted onto C₆₀ The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C₆₀. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C₆₀. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene.     

Improvement of Heater Surface Flatness and Uniformity of TiN Film Deposition

The deposition rate and the thickness uniformity of chemical vapor deposition (CVD) titanium nitride films depend on wafer temperatures. The heater surface conditions, such as flatness, roughness, and surface imperfections, can greatly affect heat transfer efficiency from the heater surface to the wafer, and the process performance. Because heater surface imperfections or “hot spots” that caused poor uniformity had to be eliminated, the origin of “hot spots” was identified by a detailed study of heater surface profiles. A better visualization of “hot spots” could be obtained by comparing wafer-chucking patterns with deposition patterns. Thus, the time needed to locate “hot spots” could be shortened. The manufacturing process was revised to prevent “hot spots” and improve heater performance.     

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.     

Mechanism of conductance switching: An optical investigation

Electronic conductance switching in devices based on thin films of an organic molecule has been studied. Switching between two conducting states has been induced by voltage pulse, while the states have been probed by optical and electrical measurements simultaneously. In situ optical measurements showed that electroreduction of molecules led to conductance switching and appearance of high-conducting state in the device. We could “write” or “erase” a state by applying electrical pulse and “read” it by measuring electronic absorbance and conductivity. The “write” and “read” processes have been carried out for many cycles to exhibit a correspondence between conductance switching and electrochromism.     

A mechanistic model for the influence of stress ratio on the LEFM fatigue crack growth behavior of metals and alloys—I. Crack-ductile materials

Concentrating on local behavior of a highly stressed zone ahead of the crack tip, a recent mechanistic approach to analyse LEFM fatigue crack growth behavior in three stages at stress ratio R = 0 is extended here to include the effect of a positive stress ratio. This paper is limited to analysing primarily the stages I and II of “crack-ductile” materials, characterised by a purely “reversed shear” (or ductile “striation”) growth mechanism in stage II. It is shown that in these materials stage I is R-sensitive and stage II is insensitive, and these can, without invoking crack closure arguments, be rationalised alternatively by considering the dominance of a K_max-controlled “Submicroscopic Cleavage” and a ΔK-controlled “ reversed shear ” fracture mechanism, respectively. Assuming Paris type power relations to hold, a predictive model is developed that contains separate growth equations with R-effect for stages I and II and shows the existence of a characteristic “master shear-curve” and a “moving pivot-point” on this curve for a class of materials. Good agreement was found between quantitatively predicted growth curves at selected R-values and a relatively large volume of available experimental data for low strength steels, aluminum alloys and titanium alloys. Besides providing more physical explanations for the observed growth behavior, the model may also be useful as a convenient alternative to crack closure for obtaining fairly accurate and conservative estimates of fatigue life for design applications.     

An Exploratory Study on Stopping a Paced Line When Incompletions Occur

This is an exploratory study of “hybrid” lines, i.e., “paced” lines whose cycle time can be extended (something like an “unpaced” line) when some task incompletions occur. Such a line should have its tasks classified into two categories; only the tasks in the first category have sufficiently high incompletion costs to justify extending the cycle time to ensure their completion. A heuristic procedure is developed to perform this classification, and we found that such hybrid lines may have a lower total cost (i.e. sum of labor and incompletion costs) than standard paced lines.     

Runout analysis in fatigue investigation

Those individual tests in a series of experiments that are not completed or must be suspended are known as “censored points,” or “runouts”. Inclusion of runouts in data analysis can be problematic, and such ad hoc approaches as ignoring the runout observation or treating it as a failure can significantly affect estimation. The methodology offered here alleviates the handling of runouts and censored data by using the maximum likelihood estimation (MLE) method to incorporate the censored data properly. The methodology is illustrated with an example problem using actual data and the affects of ad hoc approaches are illustrated.     

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.     

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 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     

Obliging Institutions and Industry Evolution: A Comparative Study of the German and UK Wind Energy Industries

This paper firstly examines the relationship between state coordination and wind energy growth by comparing the differences between UK and German institutional configurations and state involvements in the 1990s. While the EU was calling for a unified regulatory framework for its member states, the UK and Germany adopted very different renewable energy policies. The evidence of the early 1990s shows that the British government employed “deregulation” with so limited state involvement that wind energy project developers faced thorny development problems, while the German government tried to require the electricity supply industry to purchase expensive wind power by “regulation” but encountered formidable resistance. Nevertheless, both the British and German administrations later could resolve these problems through new forms of state power. This suggests that, firstly, neither “deregulation” nor “regulation” is an effective means to develop wind power with increasing electricity liberalization and regionalization. Secondly, “obliging” regulations and state powers are vital to the policy outcome by harnessing the state's institutional capacity to smooth out technology innovation and diffusion.     

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.     

ECONOMIC PRODUCTION QUOTAS FOR PULL MANUFACTURING SYSTEMS

We consider the problem of using “safety capacity” to ensure due date integrity in a pull manufacturing system and quantify the basic tradeoff between lost revenue opportunity and overtime costs. In this context, we address the question of when it is economically attractive to use “under capacity scheduling” and the problem of setting economic production quotas.

We develop four models for addressing the quota setting problem. The first three assume that quota shortfalls cannot be carried over to the next regular time production period. Models 1 and 3 assume that these shortages are made up on overtime and incur fixed or fixed plus variable costs. Model 2 does not use a capacity buffer and treats shortages as lost sales. Finally, Model 4 assumes that shortages can be backlogged to the next regular time production period at a cost. For this model, we compute both an optimal quota and an overtime “trigger,” which represents the minimum shortage for which overtime is used. We give computational results that illustrate and contrast the various models.