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.     

An Investigation of the Measurements Systems Analysis “Analytic Method” for Attribute Gages

Three automotive corporations have developed and sanctioned the recently revised reference manual entitled Measurement Systems Analysis. This “standard” contains a procedure, called the “analytic method,” whose purpose is to estimate the gage bias and gage repeatability of an attribute gage. An improved estimation procedure for this standard is presented. The improved estimation procedure yields more accurate estimates than those obtained using the procedures currently presented in the standard. In addition, the improved procedure allows more flexibility in data collection than the current test protocol. A simulation study that evaluates the estimation procedure of the current standard and compares it with the improved estimation procedure is presented. Errors that are contained in the present standard are also noted.     

“No-background” maximum likelihood analysis in HBT interferometry

We present a new “no-background” procedure, based on the maximum likelihood method, for fitting the space-time size parameters of the particle production region in ultra-relativistic heavy ion collisions. This procedure uses an approximation to avoid the necessity of constructing a mixed-event background before fitting the data.     

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.     

Edge sensitivity of “edgeless” silicon pad detectors measured in a high-energy beam

We report measurements in a high-energy beam of the sensitivity of the edge region in “edgeless” planar silicon pad diode detectors. The edgeless side of these rectangular diodes is formed by a cut and break through the contact implants. A large surface current on such an edge prevents the normal reverse biasing of this device above the full depletion voltage, but we have shown that the current can be sufficiently reduced by the use of a suitable cutting method, followed by edge treatment, and by operating the detector at a low temperature. A pair of these edgeless silicon diode pad sensors was exposed to the X5 high-energy pion beam at CERN, to determine the edge sensitivity. The signal of the detector pair triggered a reference telescope made of silicon microstrip detector modules. The gap width between the edgeless sensors, determined using the tracks measured by the reference telescope, was then compared with the results of precision metrology. It was concluded that the depth of the dead layer at the diced edge is compatible with zero within the statistical precision of ±8 μm and systematic error of ±6 μm.     

The Single Period Stochastic Plant Layout Problem

In this paper we present an optimal solution procedure for the single period stochastic plant layout problem. The procedure only requires solving a “deterministic” from-to flow matrix. This “deterministic” matrix is a weighted-average of all from-to flow matrices. Since it may be difficult to estimate the probabilities of occurrence of the various states of nature, we developed a simulation model to test the robustness of our approach. For over 26,000 problems examined, the average error of using our approach was very small, only about one-sixth of one percent.     

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”.     

“Low-Tech” Innovations

This paper is about an industrial sector which, according to the usual socio-scientific indicators, is referred to as “low-tech”, respectively as non-research intensive and which mostly comprises “traditional” industries. The interest in this sector is motivated by the contradictory situation that, on the one hand, the debate about the perspectives of modern societies focuses on the rapidly growing importance of technological innovations, knowledge and research-intensive economic sectors while, on the other hand, traditional industries make up a considerable fraction of employment and production, especially also in developed economies. On the basis of the results of extensive empirical research, this contribution tries to find answers to the basic question, whether one can speak of an innovation mode typical of the low-tech sector. The institutional based innovation systems approach forms the categorical basis of the analysis. In order to elucidate the specific features of low-tech innovations, they are, in conclusion, compared to the general characteristics of high-tech-based innovation processes.     

A novel gamma-ray imaging concept using “edge-on” microchannel plate detector

The “edge-on” illuminated microchannel plate (MCP) position-sensitive detector (PSD) is used for gamma-ray imaging for the first time. The superior position resolution of the MCP is combined with high detection efficiency due to the “edge-on” illumination mode. The results of imaging a 15 μCi ¹³⁷Cs source (662 keV quantum energy) are presented.     

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 “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.     

Experimental Design for a Granulation Process with “Priori” Criterias

Optimization techniques representr analytical tools available for the best solution to a particular problem.

Pharmaceutical product and process design problems were structured as constrained optimization problems and subsequently solved by the “a priori” optimality approach using an exchange algorithm.

The effect of the amount of added water plus granulation time and impeller speed on two properties of the granulates were investigated.

Experimental results obtained for the optimal formulation agreed well with the predictions.     

“In Vitro” Studies on Buccoadhesive Tablet Formulations of Hydrocortisone Hemisuccinate

Different bioadhesive and matrix-forming polymers were evaluated using “in-vitro” tests to identify a potentially convenient “in-vivo” formulation for the sustained delivery of hydrocortisone hemisuccinate to the oral cavity. The selected composition allows an erosion-diffusion mechanism coherent with the low hydrosolubility of the drug and with potential advantages for both the patient and the manufacturer.     

An Empirical Evaluation of the “Entrapment” Procedure for Scheduling Jobs on Identical Machines

This work empirically evaluates the “entrapment” procedure used by Barnes and Brennan's branch-and-bound algorithm to minimize total cost of tardy jobs to be processed on identical machines. Using 25 problems taken from various known sources, it is shown that entrapment does not necessarily decrease computational time required to optimally solve such a problem.     

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.     

Flexible Parts Routing in Manufacturing Systems*

We study dynamic parts routing in flexible manufacturing systems. To quantify flexibility, we develop an entropy type of measure that incorporates all the job and machine characteristics that contribute to routing flexibility. Based on this measure and the principle of “least reduction in entropy” (LRE), two operating rules, the part selection rule and the machine selection rule, are established. These rules are then applied to drive some simulated systems and compared with the “shortest processing time” (SPT) rule. It is found that LRE either outperforms or is as good as SPT in terms of makespan and machine utilization.     

Statistical analyses of highway commercial vehicle accidentst†

In a research program aimed at the assessment of more comprehensive accident analysis methods, new applications of statistical analysis procedures to commercial vehicle accidents have been investigated, and exemplary results obtained [Philipson et al., 1978], A file of some 3000 specially-detailed California Highway Patrol accident reports from two areas of California during a period of about one year in 1975–1976 provided the unique data base for the application. Computer implementation and evaluation through statistical testing of the quality of the data file were first accomplished. Then an exhaustive univariate analysis of the data was conducted to describe the file in detail. Selected sets of dependent and independent variables were then subjected to analyses of association employing contingency table analysis methods. In several cases, acceptable log-linear models to explain the variables' association were thereby established. Vehicle exposure measured in vehicle miles traveled for each vehicle category was introduced into one of the analyses to assess its impact on the set of significant interactions; it was indeed found to be important, albeit accuracy in its estimation was problematical. This estimation was carried out by two independent methods; a “direct” procedure based on a series of linear extrapolations of basic State of California commercial vehicle traffic data, and an “induced” estimation procedure essentially employing only data in the accident reports. The results of the two methods exhibited some common trends, but otherwise differed considerably. The results of the research effort, highlighted in this article, indicated the value of the methods investigated, and so of the detailed accident report files necessary for their use. They also strongly illuminated the areas of greatest difficulty in the application of these methods, basically associated with accident data quality and exposure estimation accuracy, and general directions for their improvement.     

Mechanical behaviour of a two-phase material from the behaviour of its components: Interface modelling by finite element method

In this paper, the principle of a solution for “thermal” connection between two solids is analyzed. We shows results given by the solution applied to the mechanical behaviour of a γ/γ′ two-phase material and to “artificial” structures obtained from modern techniques for epitaxial deposit. It appears that the use of a true or fictitious thermal loading constitutes a simple “connection” procedure, but is particularly coherent with the mechanics of two-phase crystalline materials with different lattice parameters. It would be interesting to apply the model to real structures, with misfit and interfacial dislocations.     

Development of a “Continuous-Flow Adhesion Cell” for the Assessment of Hydrogel Adhesion

The purpose of this study was to develop an in vitro perfusion technique or “continuous-flow adhesion cell” model to predict the in vivo performances of different mucoadhesive drug delivery systems based on hydrogels. Two studies were performed, either using a rabbit small intestine or a polyethylene surface; the adhesion of four gels—two poly(acrylic acid)s (PAAs) (carbomer [CM] and polycarbophil [PC]), an ethyleneoxide-propyleneoxide block copolymer (Poloxamer®407 [PM]), and a polysaccharide (scleroglucane [SG])—were evaluated. In this respect, scleroglucane was used as a control. The adhesiveness of the different gels for both supports is in accordance with that described in the literature, that is, polycarbophil adhered more strongly than carbomer, which itself adhered more strongly than poloxamer. This study proved that the gels adhere more strongly to the polyethylene tube than to the rabbit small intestine, thus indicating that evidence for adhesion properties does not need any presence of mucus. Therefore, our in vitro model could be a good method, more precise and more simple than an ex vivo technique, to predict the bioadhesion of gelified devices.     

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.