Towards a deeper understanding of managerial green investment patterns – a USA–Germany comparison

Green investments are crucial mechanisms for translating green operation strategies into managerial action. We examine the impact of external pressures on green investment patterns in terms of their scope, type and time horizon across 251 German and US managers. A scenario-based experiment was conducted using a 2 × 2 × 2 factorial design in which managers were assigned to high and low consumer, community, and resource treatment groups before being asked to make green investment decisions. Our hypotheses are developed based on resource advantage theory and tested in a number of regression models. The results demonstrate that German and US managers respond differently to external pressures in their green investment decisions. Regarding the scope of green investments, German and US managers invest differently if end consumer pressure increases and partially differently if resource scarcity increases, but they act in a similar way if community pressure increases. Moreover, we detected specific variations in the type and time horizon of green investments across US and German managers. The theoretical and practical implications of these findings for green operations management research and for firms operating in multinational settings are explained.     

Nanoindentation in more than one dimension – Experimental challenges and opportunities

The current status of nanoindentation apparatus and the requirements for extension to more than one dimension of loading is described. It is possible, though not trivial, to adequately characterise the stiffnesses and couplings present in a frictional contact and thus expand the present use of nanoindentation to important new areas. The example of static friction is discussed to show that complete machine characterisation is required if true interface mechanical properties and friction coefficients are to be correctly measured.     

Three-dimensional performance surfaces–a tool for analysing and estimation of production system performances

This paper presents a new method to describe, analyse and estimate production system performances. Work-in-process (units), lead time (number of time units spent in the production system for each unit) and throughput (number of produced units per time unit) are basic performance measures, also used in this article. It is essential for industry to know about relations between system parameters and system performances in existing systems, and in not yet implemented system alternatives. Different performances are achieved by adjusting system parameters. Trade-offs between system parameters and its different performances are necessary to stay efficient and competitive in today's market. Queuing theory and simulation can help the decision makers to estimate system performances of existing and not yet implemented systems. When the complexity increases queuing theory becomes cumbersome, very difficult and eventually impossible to use. A single simulation presents limited information. Multiple simulations are necessary to ensure that the best alternative is chosen. A high number of simulations demand a lot of computer time and resources. Reduction of runs is desirable even with cheaper computer equipment. Currently, traditional two-dimensional charts are the only tools to present and analyse system performances. This article presents a new surrogate model for easier estimation and presentation of system performances, their internal relations, and relations to the system parameters. With the new surrogate model, system performances based on simulations are presented as positions in a three-dimensional environment. Parametric curves and surfaces of Bezier type are generated and adapted to these positions. System performances of other system alternatives can then be estimated without explicit simulation. The number of simulation calculations can thereby be moderated. The method is illustrated with a small production line system.     

Optimal control of a stochastic production–inventory system under deteriorating items and environmental constraints

In this paper, we present an optimal control model of a stochastic production–inventory with deteriorating items, emission tax and pollution abatement investment. In our model, the emission tax is levied on the firm’s environmental obsolescence rate of technology rather than the total amount of the environmental externality. Our objective is to apply Hamilton–Jacobi–Bellman (HJB) equation to solve the stochastic production–inventory system with deteriorating items, emission tax and pollution abatement investment; and derive the optimal production rate and pollution abatement investment rate that maximise the objective function value. The results are discussed with some illustrative examples for different demand rate functions, and sensitivity analysis is conducted to study the effect of changing the parameters and coefficients on the objective function value.     

Evaluation of reverse referral partnership in a tiered hospital system – A queuing-based approach

Reverse referral implies referring patients from a comprehensive hospital to a community healthcare centre. In recent years, it has become popular for post-acute care in the tiered Chinese hospital system as it helps achieve more balanced utilisation between facilities at different levels. Nevertheless, it remains unclear how to implement the reverse referral partnership given the likely conflicting interests between the involved hospitals. In this paper, we evaluate a reversal referral partnership involving one hospital of each type, for which we develop queuing models for the two hospitals to capture multiple patient waits, services and transitions, with reverse referral in place. We use queuing-based performance outcomes to evaluate the profitability of each hospital and its willingness to join the partnership. We combine the above evaluations to further assess the partnership effectiveness. Through this work, we expect to provide policy insights to the government for forming hospital partnerships effectively.     

Understanding bioenergy production and optimisation at the nanoscale – a review

ABSTRACT

Nanotechnology has an increasingly large impact on a wide range of biotechnological, pharmacological and pure technological applications. Its current use in bioenergy production from biomass is very limited. This paper examines the potential interrelationships between nanotechnology and bioenergy production through a comprehensive literature review and analysis of data from biomass characterisation studies. The aim of this review is to indicate how nanotechnology can be applied in biomass-to-bioenergy conversion. This study shows currently nanotechnology has been applied in the production of only two types of biomass, i.e. sludge and algae. Hence, interaction of nanomaterials with active sludge and algal cells were examined. Our extensive literature review indicates that anaerobic digestion process in sludge can potentially be enhanced by using magnetite nanoparticles, which gives higher methane yields. On the other hand, nanosilver reduces growth and causes adverse effects on the morphology of green algae. This process for bioenergy generation has already been successfully applied to sludge and algae biomass. Our study confirms that the process can also be used in the production of bioenergy from the other biomasses, such as agricultural wastes and industrial residues. Outcomes of this work will be an important tool for implementing nanotechnology in bioenergy research.     

A matrix system for production management—a description and an application

This paper presents a morphological model of an integrated production management system. The model is designed as an intersecting point structure. The two dimensions in the model are the phases in a control cyclus and the objects of control. Each point in the structure represents an activity in the total production management system.

The model has proved successful as a tool for analysis and redesign of of production management systems. An example of the application of the model is given.     

Manufacturers’ coalition under a price elastic market – a quadratic production game approach

The paper addresses a supply network design problem in which a set of enterprises decides to organise itself as a multi-stage supply network by resource sharing and production coordination. A biform game theory formulation of the problem is obtained by combining the cooperative sub-game in the manufacturing network with the strategic sub-game of the Stackelberg type between the retailer and the manufacturers’ network. As a result of the interaction between these two sub-games, a new type of cooperative game, the quadratic production game, is formulated to describe the supply network design problem under anticipated price elastic demands from the market. The key problem of coalitional stability is addressed through the properties of rationality and fairness of the profit sharing agreement. We prove that the game is non-convex in general and thus, the fair solution given by the Shapley value allocation is not always rational. It is proposed to reinforce the coalition stability by selecting a minimal set of partner enterprises achieving the maximal expected profit and applying a profit sharing policy with guaranteed fairness restricted to the member enterprises.     

Approaching maximum-likelihood performance with reduced complexity for a double space?time transmit diversity system

A reduced-complexity detector approaching maximum-likelihood (ML) detection performance is presented for the double space-time transmit diversity system. The proposed scheme exploits both the special structure of equivalent channel matrix and decision-feedback detection. This accounts for accomplishing near-ML or ML performance with significantly relieved computational loads. Moreover, to moderate the average complexity, several distance metric selection criteria are proposed. We can control performance and computational savings according to different distance metric selection rules. Numerical results show that the proposed detector requires significantly fewer computations than that of the Schnorr-Euchner sphere-decoding algorithm in terms of both the worst-case and the average complexity.     

On a more generalized theory of the pull-out test from an elastic matrix Part II—Application to a polypropylene-cement system

The theoretical treatment presented in Part I of this work is applied to a system which consists of polypropylene (PP) yarns embedded in a cement matrix. The maximum pull-out force values, obtained from specimens produced with different embedment lengths, normal stresses and yarn thicknesses are analyzed by using the formulae deduced in Part I. The results show that increasing the above three parameters brought about an increase of the maximum pull-out forces. When comparison is made with the theoretical formulae, the interfacial shear strength of the PP-cement system is calculated to possess values between 0·8 and 1·2 MPa, according to the amount of pressure applied on the system. The hexagonal close-packed array is employed to describe the way the PP fibers are arranged in the yarn, and found suitable to estimate the effective area of contact of the fiber-matrix interface.     

Critical attributes of transdermal drug delivery system (TDDS) – a generic product development review

Bioequivalence testing of transdermal drug delivery systems (TDDS) has always been a subject of high concern for generic companies due to the formulation complexity and the fact that they are subtle to even minor manufacturing differences and hence should be clearly qualified in terms of quality, safety and efficacy. In recent times bioequivalence testing of transdermal patches has gained a global attention and many regulatory authorities worldwide have issued recommendations to set specific framework for demonstrating equivalence between two products. These current regulatory procedures demand a complete characterization of the generic formulation in terms of its physicochemical sameness, pharmacokinetics disposition, residual content and/or skin irritation/sensitization testing with respect to the reference formulation. This paper intends to highlight critical in vitro tests in assessing the therapeutic equivalence of products and also outlines their valuable applications in generic product success. Understanding these critical in vitro parameters can probably help to decode the complex bioequivalence outcomes, directing the generic companies to optimize the formulation design in reduced time intervals. It is difficult to summarize a common platform which covers all possible transdermal products; hence few case studies based on this approach has been presented in this review.     

Empowering production workers with digitally facilitated knowledge processes – a conceptual framework

Recent digital advancements, including social software, mobile technologies and augmented reality, offer promising opportunities to empower knowledge workers in their production environment by leveraging their knowledge processes, decision-making skills and social interaction practices. This paper proposes a conceptual framework for empowering workers in industrial production environments with digitally facilitated knowledge management processes. The framework explores four concrete facets of digital advancements that apply to a wide range of knowledge processes and production strategies in manufacturing companies. Each of these advancements are capable of supporting one specific facet of the individual knowledge management processes of workers; knowledge transfer, discovery, acquisition and sharing. The study contributes to the production research community by aligning emerging digital technologies and current trends in advanced manufacturing environments to benefit workers and improve job satisfaction, efficiency and productivity. The paper also contains suggestions about developing innovative solutions for production environments that support workers with digital technologies for flexible production.     

Physicochemical properties of an Al – C composite in two-stage production

A new two-stage production process of composite aluminum-based fibrous materials is investigated. The first stage is infiltration, i.e., moistening of a bundle of carbon fibers with a CuSn10Ti17 transition alloy. The main aim of this procedure is to form a barrier layer, which prevents the penetration of liquid aluminum into fibers. This transition layer contains predominantly titanium carbide (TiC). In the second stage, the primary base of the CuSn10Ti17 alloy is replaced by an aluminum one. Results of metallographic studies and a microanalysis of the chemical composition on the interface confirm the efficiency of the proposed method. It is shown that the processes of infiltration and change of the primary base for the final one occurs at a temperature of 1000°C for 1 – 1.5 and 4 min.     

Concept of energy efficient technological system: Machine tool – cutting tool – workpiece

This study deals with the concept of increasing energy efficiency by means of decreasing the energetic losses by using advanced composite machine tool components and interfaces characterized by low friction, and high wear resistance. Moreover, this study provides experimental results of damping property measurements and characteristic time domain curves of the fibre, particle, and sandwich composites, underlining the advantages of such composite types in terms of dynamic loading. Furthermore, it provides an analysis on the usage of thin films (coatings) and energy consumption in terms of cutting conditions. The study analyses the cutting tool geometry and shape of cutting edge that positively affect the cutting forces and chip flow direction, and avoid the energy-intensive restricted cutting effect. Respecting the results of the analyses of mentioned effects contributes to increasing the energy efficiency of the machine tool-cutting tool-workpiece system.     

GERT analysis of a single conveyor system†

Graphical Evaluation and Review Technique (GERT) has been applied to the analysis of the discrete conveyor model for service time distributions which are general but bounded and where there is no storage at work stations and no recirculation. The model is described by states with the Markovian property. The GERT analysis gives a visual representation of the conveyor system and useful information in the conveyor system design.     

Transient modeling of a flash tank vapor injection heat pump system – Part I: Model development

This two-part article explores the dynamic behavior of a flash tank vapor injection heat pump system from a numerical simulation perspective. Part I provides a first-principles model describing the transient heat transfer and flow phenomena of the system with detailed modeling techniques for each component. The vapor injection scroll compressor is analyzed with the internal heat transfer between the refrigerant and metallic parts taken into account. Lumped-parameter models are developed for the flash tank and expansion devices. Heat exchangers are modeled using a finite volume approach and accounting for the complex tube circuitry. The separated flow model without interfacial exchange is utilized for two-phase flows in order to incorporate an appropriate void fraction model so that a more accurate prediction for refrigerant mass distribution can be achieved. The modular nature of the component models allows flexibility in the system configuration. Transient simulations are carried out for start-up and shut-down operations. A detailed comparison of model predictions against experimental data is presented in the companion paper.     

Detecting bottlenecks in serial production lines – a focus on interdeparture time variance

This work addresses an important problem in industry – locating the bottleneck in a production line – and suggests a practical approach to accomplish that end. We describe and validate, using discrete event simulation, a novel method of bottleneck detection in open, asynchronous serial production lines with finite buffers. The technique uses a single measure – station interdeparture time variance – to locate the system bottleneck. The proposed method is compared to other bottleneck detection approaches and it is shown that the proposed method performs as well and sometimes better than other methods. We conclude that the proposed approach has a number of significant advantages. It is easy to use and implement, not requiring data about failure and repair times, raw process times, buffer sizes, etc., but instead uses a single piece of easily obtained real-time production line data – station work-in-process (WIP) interdeparture time. The proposed method can identify production constraints without the need to build an analytical or simulation model, is well suited for use in industry, and can be readily implemented in standard simulation tools.     

Concepts to estimate the endurance limit of notched parts – A statistical evaluation using a broad database for P/M steels

Structural parts made of P/M (powder metallurgy) materials are increasingly used in lightweight construction for high performance applications. Due to their low density, they substitute for wrought steel in automotive applications e.g. gears or synchronizer hubs. This raises the need for reliable fatigue design concepts. Different concepts to estimate the endurance limit of notched components have been examined and statistically evaluated based on a broad database of various steel-based P/M materials. The sensitivity to notches of P/M materials is highly dependent on the chemical composition and the density, which makes it difficult to fit empirical models for different P/M materials. El Haddad’s fictitious crack length proves to be a good parameter to account for this dependency. Using the theory of critical distances, the fatigue properties of a material can be transferred to parts effectively and with low scatter.     

Service levels,system cost and stability of production–inventory control systems

Production-inventory control system models have been analysed in the literature either in terms of their stability against demand fluctuations or in terms of their service level and cost performance under uncertain demand. This article analyses the production-inventory system performance in terms of service level (i.e. order fill rate) and average system costs, under stable settings of the control parameters. The classical automatic pipeline variable inventory and order-based production control system has been modified by explicitly modelling safety stock to help achieve higher services levels in the face of random demand. The stability of the system is affected by the control parameters: fractional rates of adjustment of work-in-process and inventory. However, the service level and average cost are affected by the control parameters as well as the smoothing factor in demand forecasting. This article puts forward five propositions which give light to general system performance based on the parameters selection. Intensive simulation experiments have also been carried out to reveal the performance variations within the stable region, leading to further insights on the system behaviour. The managerial insights which can assist proper tuning of systems to help achieve the desired performances have been discussed.     

Research evaluation. Part II: gender effects of evaluation: are men more productive and more cited than women?

Productivity and citedness of the staff of a German medical research institution are analyzed. It was found in our previous study (Pudovkin et al.: Scientometrics, doi:10.1007/s11192-012-0659-z, 2012) that male scientists are more prolific and cited more often than female scientists. We explain in our present study one of the possible causes for obtaining this result with reference to Abramo et al. (Scientometrics 84(3): 821?C833, 2009), who found in the small subgroups of star scientists a higher performance of male star scientists with respect to female star scientists; but in the remaining complementary subpopulations the performance gap between the two sexes is marginal. In agreement with Abramo et al. (2009), in our small subgroup of star scientists a higher performance of male star scientists with respect to female star scientists could be found. Contrasting, in the large complementary subgroup even a slightly higher performance of female scientists with respect to male scientists was identified. The last is even stronger expressed in favor of women than Abramo??s result that the performance gap between the two sexes is truly marginal. In addition to Abramo et al. (2009), we already found in our previous study, special indexes characterizing the quality of papers (but not quantity) are not substantially different among sexes compared.