Academic productivity correlated with well-being at work

Do the best Italian academics move abroad? What is the academic productivity of an Italian researcher working in Italy compared with one working abroad? Does academic productivity depend on their well-being at work? The aim of this study is to find explanations for these questions and to demonstrate the relationship that exists between academic productivity and organizational well-being and work, both for researchers who are Italian emigrants abroad (project IRA) and for those who remain in Italy (IRI project).This goal was achieved through two surveys. Where there is an atmosphere of a wellness organization, it creates a productive work environment (vision abroad); conversely, a poor working environment that is associated with an organizational system that is below the average level negatively affects the overall academic productivity (in Italy). We can confirm that working environments with better organizational climate produce more productive academics.     

Optimal control with responses and control force constraints

Abstract

In order to assure safety and serviceability, structural responses are kept within certain limits by active control methods. Control forces as well as responses (displacement and velocity) are considered constraints in an optimal control system. The exact solution of the optimal control system under the aforementioned constraints is derived in the first part of the paper. An approximate solution is also suggested in the paper. An example dealing with a six‐story building is presented in the last part of the paper to demonstrate the application of the approximate approach.     

Phase shifting Fizeau interferometry of front and back surfaces of optical flats

The interpretation of Fizeau interferograms of optical flats is not straightforward because they are composed of more than two reflections. This results in a confusing fringe pattern. There are three main contributions to the interferogram given by the reflections from the reference surface, the front and the rear surface of the sample. We present a new to the best of our knowledge solution to the problem. We use phase shifting measurements of the wave fields, which are reflected by and transmitted through the sample. This eliminates the need for the suppression of reflections by immersion or other methods. As an illustration of this method, several examples will also be presented.     

一种最优滑模控制算法及其仿真应用

针对某机电伺服跟踪系统存在扰动和系统参数摄动的情况,提出了一种带有积分补偿的最优滑模变结构控制算法,并给出了获得切换函数、积分增益和控制函数的方法。仿真结果表明,这种新的控制算法比经典控制方法的效果更好。它能够获得灵敏的跟踪效果,提高了系统响应的快速性,具有较好的动态性能和鲁棒性,并消除了抖振。此控制系统结构简单,易于实现。     

Identification of patterns in control charts for processes with statistically correlated noise

In real industrial scenarios, if the quality characteristics of a continuous or batch production process are monitored using Shewhart control charts, there could be a large number of false alarms about the process going out of control. This is because these control charts assume that the inherent noise of the monitored process is normally, independently and identically distributed, although the assumption of independence is not always correct for continuous and batch production processes. This paper presents three control chart pattern recognition systems where the inherent disturbance is assumed to be stationary. The systems use the first-order autoregressive (AR(1)), moving-average (MA(1)) and autoregressive moving-average (ARMA(1,1)) models. A special pattern generation scheme is adopted to ensure generality, randomness and comparability, as well as allowing the further categorisation of the studied patterns. Two different input representation techniques for the recognition systems were studied. These gave nearly the same performance for the MA(1) and ARMA(1,1) models, while the raw data yielded the highest accuracies when AR(1) was used. The effect of autocorrelation on the pattern recognition capabilities of the developed models was studied. It was observed that Normal and Upward Shift patterns were the most affected.     

InP 层对正面及背面入光 PIN 探测器响应度影响研究

InP盖层对光的吸收及入射光在探测器多界面间的多次反射,使InP层对InGaAs/InPPIN探测器的响应度产生了很大的影响。本文测量了正面和背面入光PIN探测器的响应度,并与测量的InP晶片透射率及模拟的透射率进行比较,分析了InP层对正面及背面入光PIN探测器响应度的影响。结果表明,随着InP层厚度的增加,响应度峰与峰的间隔Δλ不断减小,波形越来越密集。所以正面入光探测器的响应度起伏比较明显,且随着InP层厚度的增加,响应度极值对应的波长发生红移。背面入光探测器的响应度非常密集而成为准连续的带状。     

Optimal control of epidemics in metapopulations

Little is known about how best to deploy scarce resources for disease control when epidemics occur in different but interconnected regions. We use a combination of optimal control methods and epidemiological theory for metapopulations to address this problem. We consider what strategy should be used if the objective is to minimize the discounted number of infected individuals during the course of an epidemic. We show, for a system with two interconnected regions and an epidemic in which infected individuals recover and can be reinfected, that equalizing infection in the two regions is the worst possible strategy in minimizing the total level of infection. Treatment should instead be preferentially directed at the region with the lower level of infection, treating the other subpopulation only when there is resource left over. The same strategy holds with preferential treatments of regions with lower levels of infection when quarantine is introduced.     

Dynamic scheduling of batch servers with compatible product families

Dynamic scheduling is considered for batch processing machines. Research is motivated by the burn-in ovens found in semiconductor manufacturing. So far, research in this field has concentrated on control strategies that assume batches to be homogeneous, i.e. products should all belong to the same family. However, burn-in ovens may allow simultaneous processing of alternative families of products. Each family may set different requirements to processing times. The processing time of a batch is equal to the longest processing time required among all products in the batch. A new scheduling approach is proposed that addresses these situations. The objective is to minimize average flow time per product for the batch operation. The so-called look-ahead strategy adapts its scheduling decision to shop status, which includes information on a limited number of near future arrivals. The potential of the new strategy is demonstrated by an extensive simulation study.     

Optimal approximate designs for comparison with control in dose-escalation studies

Consider an experiment, in which a new drug is tested for the first time on human subjects, namely healthy volunteers. Such experiments are often performed as dose-escalation studies: a set of increasing doses is preselected; individuals are grouped into cohorts; and in each cohort, dose number i can be administered only if dose number \(i-1\) has already been tested in the previous cohort. If an adverse effect of a dose is observed, the experiment is stopped, and thus, no subjects are exposed to higher doses. In this paper, we assume that the response is affected both by the dose or placebo effects and by the cohort effects. We provide optimal approximate designs for estimating the effects of the drug doses compared with the placebo with respect to selected optimality criteria (E-, MV- and LV-optimality). In particular, we prove the optimality of the so-called Senn designs with respect to all of the studied optimality criteria, and we provide optimal extensions of these designs for selected criteria.     

Approximation and analysis of a call center with flexible and specialized servers

This paper describes a decomposition algorithm to estimate the performance of a call center with two types of customers and two server categories. In this system specialized servers can process only one customer type, while flexible servers handle both types. The algorithm divides the systems state space into regions, and simple approximate models find the conditional system performance within each region. While the procedure described here is tailored for a system with a priority queue discipline and two customer classes, it can be adapted for systems with FCFS queue disciplines and for systems with more than two customer types. Performance measures generated by the procedure are sufficiently accurate for many service system design decisions, such as setting telephone call center staffing levels and long-term capacity planning. The procedure is also extremely fast, and its computational requirements do not grow with system congestion. Numerical tests demonstrate that its running time is significantly lower than traditional numerical methods for generating approximations. As an example of its use, we employ the procedure to demonstrate the benefits of server flexibility in a particular telephone call center.The author thanks Gregory Dobson, who participated in the initial consulting project and problem formulation, as well as Paul Schweitzer, Harry Groenevelt, and two anonymous referees for their helpful suggestions.     

Optimal control of sprinklers in compartment fires

There is no doubt that increased application of sprinkler protection through a building can significantly reduce fire losses. In many compartment fires, the water damage is far more extensive than the flame damage. This paper examines the possibility of controlling the flow of water from sprinklers in an optimal way so as to minimize the water damage and the overall property damage. Two cases are considered. The first when the water damage is proportional to the total amount of water and the second when it is proportional to the integral of the square of the water flow rate. © 1997 John Wiley & Sons, Ltd.     

Optimal control of melt-spinning processes

An optimal-control problem for a mathematical model of a melt-spinning process is considered. Newtonian models with constant viscosity and temperature-dependent viscosity are used to describe the rheology of the polymeric material, the fiber is made of. The extrusion velocity of the polymer at the spinneret, as well as the velocity and temperature of the quench air serve as control variables. A constrained-optimization problem is derived and a first-order optimality system is set up to obtain the adjoint equations. Numerical solutions are carried out using a steepest-descent algorithm.     

Evaluation of Shewhart time-between-events-and-amplitude control charts for correlated data

In recent years, several techniques based on control charts have been developed for the simultaneous monitoring of the time interval T and the amplitude X of events, known as time-between-events-and-amplitude (TBEA) charts. However, the vast majority of the existing works have some limitations. First, they usually focus on statistics based on the ratio $\frac{X}{T}$, and second, they only investigate a reduced number of potential distributions, that is, the exponential distribution for T and the normal distribution for X. Moreover, until now, very few research papers have considered the potential dependence between T and X. In this paper, we investigate three different statistics, denoted as Z₁ , Z₂ , and Z₃ , for monitoring TBEA data in the case of three potential distributions (gamma, normal, and Weibull), for both T and X, using copulas as a mechanism to model the dependence. An illustrative example considering times between machine breakdowns and associated maintenance illustrates the use of TBEA control charts.     

Optimal control of ingot heating in flow-through furnaces

The algorithm developed here allows the ingot-heating conditions in a furnace corresponding to the least skin formation to be determined. The influence of the furnace atmosphere on skin growth in heating is investigated.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 61, No. 2, pp. 199–203, August, 1991.     

Optimal control of production and remanufacturing in a simple recovery model with linear cost functions

One aspect in reverse logistics concerns returns of used products and recovery for another life cycle. Remanufactured parts can be used for assembly of new products or the entire (upgraded) product can be sold again. Limitations and enormous waste disposal cost, the duty for manufacturers to take back used products from customers, and the fact that returned products can be regarded as a resource for material requirements are reasons for a consideration of product recovery. In this paper, we present an optimal control approach to optimize the production, remanufacturing, and disposal strategy with respect to dynamic demand and returns.