The Generalized Malmquist index and capacity utilization change: an application to the Italian manufacturing, 1989-1994

Several indices of plant capacity utilization based on the concept of best practice frontier have been proposed in the literature (Fare et al. 1992; De Borger and Kerstens, 1998). This paper suggests an alternative measure of capacity utilization change based on Generalized Malmquist index, proposed by Grifell-Tatje' and Lovell in 1998. The advantage of this specification is that it allows the measurement of productivity growth ignoring the nature of scale economies. Afterwards, this index is used to measure capacity change of a panel of Italian firms over the period 1989-94 using Data Envelopment Analysis and then its abilities of explaining the short-run movements of output are assessed.

Outsourcing decisions:the case of parallel production

Purpose – The purpose of this paper is to investigate an underexplored aspect of outsourcing involving a mixed strategy in which parallel production is continued in-house at the same time as outsourcing occurs. Design/methodology/approach – The study applied a multiple case study approach and drew on qualitative data collected through in-depth interviews with wood product manufacturing companies. Findings – The paper posits that there should be a variety of mixed strategies between the two governance forms of “make” or “buy.” In order to address how companies should consider the extent to which they outsource, the analysis was structured around two ends of a continuum: in-house dominance or outsourcing dominance. With an in-house-dominant strategy, outsourcing complements an organization's own production to optimize capacity utilization and outsource less cost-efficient production, or is used as a tool to learn how to outsource. With an outsourcing-dominant strategy, in-house production helps maintain complementary competencies and avoids lock-in risk. Research limitations/implications – This paper takes initial steps toward an exploration of different mixed strategies. Additional research is required to understand the costs of different mixed strategies compared with insourcing and outsourcing, and to study parallel production from a supplier viewpoint. Practical implications – This paper suggests that managers should think twice before rushing to a “me too” outsourcing strategy in which in-house capacities are completely closed. It is important to take a dynamic view of outsourcing that maintains a mixed strategy as an option, particularly in situations that involve an underdeveloped supplier market and/or as a way to develop resources over the long term. Originality/value – The concept of combining both “make” and “buy” is not new. However, little if any research has focussed explicitly on exploring the variety of different types of mixed strategies that exist on the continuum between insourcing and outsourcing.

Improved lithium storage properties of electrospun TiO2 with tunable morphology:from porous anatase to necklace rutile

Three-dimensional TiO2 with tunable morphology and crystalline phase was successfully prepared by the electrospinning technique and subsequent annealing. Porous-shaped anatase TiO2, cluster-shaped anatase TiO2, hierarchical-shaped rutile (minor) TiO2 and nano-necklace rutile (major) TiO2 were achieved at 500, 600, 700 and 800°C, respectively. The mechanism of the formation of these tailored morphologies and crystallinity was investigated. Lithium insertion properties were evaluated by galvanostatic and potentiostatic modes in half-cell configurations. By combining the large surface area, open mesoporosity and stable crystalline phase, the porous-shaped anatase TiO2 exhibited the highest capacity, best rate and cycling performance among the four samples. The present results demonstrated the usefulness of three-dimensional TiO 2 as an anode for lithium storage with improved electrode performance. © 2013 The Royal Society of Chemistry.

Hierarchical ZnO “rod like” architecture synthesized via reverse micellar route for improved photocatalytic activity

Hierarchical ZnO “rod like” architecture was successfully synthesized via reverse micellar route and characterized by various techniques. The FESEM studies show controlled decomposition of zinc oxalate into ZnO “rod like” architecture at 500 °C with slow heat rate at 1°/min. Interestingly, improved photocatalytic activity was observed for the degradation of Rhodamine B, due to the self assembly of hexagonal nanoparticles of zinc oxide forming hierarchical ZnO “rod like” architecture which can greatly enhance the light utilization rate due to its special architecture and enlarge the specific surface area, providing more reaction sites and promoting mass transfer. More importantly, the reusability studies of this architecture were most economical.

Quality-driven resource utilization methods for video streaming in wireless communication networks

This research is focused on the optimisation of resource utilisation in wireless mobile networks with the consideration of the users’ experienced quality of video streaming services. The study specifically considers the new generation of mobile communication networks, i.e. 4G-LTE, as the main research context. The background study provides an overview of the main properties of the relevant technologies investigated. These include video streaming protocols and networks, video service quality assessment methods, the infrastructure and related functionalities of LTE, and resource allocation algorithms in mobile communication systems. A mathematical model based on an objective and no-reference quality assessment metric for video streaming, namely Pause Intensity, is developed in this work for the evaluation of the continuity of streaming services. The analytical model is verified by extensive simulation and subjective testing on the joint impairment effects of the pause duration and pause frequency. Various types of the video contents and different levels of the impairments have been used in the process of validation tests. It has been shown that Pause Intensity is closely correlated with the subjective quality measurement in terms of the Mean Opinion Score and this correlation property is content independent. Based on the Pause Intensity metric, an optimised resource allocation approach is proposed for the given user requirements, communication system specifications and network performances. This approach concerns both system efficiency and fairness when establishing appropriate resource allocation algorithms, together with the consideration of the correlation between the required and allocated data rates per user. Pause Intensity plays a key role here, representing the required level of Quality of Experience (QoE) to ensure the best balance between system efficiency and fairness. The 3GPP Long Term Evolution (LTE) system is used as the main application environment where the proposed research framework is examined and the results are compared with existing scheduling methods on the achievable fairness, efficiency and correlation. Adaptive video streaming technologies are also investigated and combined with our initiatives on determining the distribution of QoE performance across the network. The resulting scheduling process is controlled through the prioritization of users by considering their perceived quality for the services received. Meanwhile, a trade-off between fairness and efficiency is maintained through an online adjustment of the scheduler’s parameters. Furthermore, Pause Intensity is applied to act as a regulator to realise the rate adaptation function during the end user’s playback of the adaptive streaming service. The adaptive rates under various channel conditions and the shape of the QoE distribution amongst the users for different scheduling policies have been demonstrated in the context of LTE. Finally, the work for interworking between mobile communication system at the macro-cell level and the different deployments of WiFi technologies throughout the macro-cell is presented. A QoEdriven approach is proposed to analyse the offloading mechanism of the user’s data (e.g. video traffic) while the new rate distribution algorithm reshapes the network capacity across the macrocell. The scheduling policy derived is used to regulate the performance of the resource allocation across the fair-efficient spectrum. The associated offloading mechanism can properly control the number of the users within the coverages of the macro-cell base station and each of the WiFi access points involved. The performance of the non-seamless and user-controlled mobile traffic offloading (through the mobile WiFi devices) has been evaluated and compared with that of the standard operator-controlled WiFi hotspots.

Kinetic and hydraulic studies in high-rate biological filters

Most published work on either low- or high-rate biological filters covers one of three topics: kinetics, microbiology/ecology or hydraulics. These areas have been re-examined together for high-rate filters in order to further integrate them and enable appropriate utilization of low-rate filter experience.

Evaluating the capacity of long haul soliton transmission

We review recent developments in the use of optical solitons for communication systems spanning transoceanic distances. The implementation of "soliton control" to alleviate the detrimental impact of effects such as amplifier noise is shown to be critical for obtaining advantages over competing technologies. The potential performance of two control strategies, namely straight line filtering and synchronous phase modulation, is examined in detail. Design diagrams are used to determine the maximum permissible amplifier spacing, which is a key determinant of system economics. To focus the enquiry, two example system spans are taken, representing transatlantic and transpacific distances. It is concluded that straight line filtering provides very little improvement over a basic design without control. However synchronous phase modulation, which may be implemented using a handful of actively driven components, provides very substantial benefits. These may be used either to extend the overall bit-rate-distance product of the system or to increase the amplifier spacing at more moderate capacities.

Capital markets and the market structure of foreign investments

Contrary to the long-received theory of FDI, interest rates or rates of return can motivate foreign direct investment (FDI) in concert with the benefits of direct ownership. Thus, access to investor capital and capital markets is a vital component of the multinational’s competitive market structure. Moreover, multinationals can use their superior financial capacity as a competitive advantage in exploiting FDI opportunities in dynamic markets. They can also mitigate higher levels of foreign business risks under dynamic conditions by shifting more financial risk to creditors in the host economy. Furthermore, the investor’s expectation of foreign business risk necessarily commands a risk premium for exposing their equity to foreign market risk. Multinationals can modify the profit maximization strategy of their foreign subsidiaries to maximize growth or profits to generate this risk premium. In this context, we investigate how foreign subsidiaries manage their capital funding, business risk, and profit strategies with a diverse sample of 8,000 matched parents and foreign subsidiary accounts from multiple industries in 38 countries.We find that interest rates, asset prices, and expectations in capital markets have a significant effect on the capital movements of foreign subsidiaries. We also find that foreign subsidiaries mitigate their exposure to foreign business risk by modifying their capital structure and debt maturity. Further, we show how the operating strategy of foreign subsidiaries affects their preference for growth or profit maximization. We further show that superior shareholder value, which is a vital link for access to capital for funding foreign expansion in open market economies, is achieved through maintaining stability in the rate of growth and good asset utilization.

Adaptive rate control of dedicated short range communications based vehicle networks for road safety applications

Dedicated Short Range Communication (DSRC) is a promising technique for vehicle ad-hoc network (VANET) and collaborative road safety applications. As road safety applications require strict quality of services (QoS) from the VANET, it is crucial for DSRC to provide timely and reliable communications to make safety applications successful. In this paper we propose two adaptive message rate control algorithms for low priority safety messages, in order to provide highly available channel for high priority emergency messages while improve channel utilization. In the algorithms each vehicle monitors channel loads and independently controls message rate by a modified additive increase and multiplicative decrease (AIMD) method. Simulation results demonstrated the effectiveness of the proposed rate control algorithms in adapting to dynamic traffic load.

QoS guarantee with adaptive transmit power and message rate control for DSRC vehicle network based road safety applications

Quality of services (QoS) support is critical for dedicated short range communications (DSRC) vehicle networks based collaborative road safety applications. In this paper we propose an adaptive power and message rate control method for DSRC vehicle networks at road intersections. The design objective is to provide high availability and low latency channels for high priority emergency safety applications while maximizing channel utilization for low priority routine safety applications. In this method an offline simulation based approach is used to find out the best possible configurations of transmit power and message rate for given numbers of vehicles in the network. The identified best configurations are then used online by roadside access points (AP) according to estimated number of vehicles. Simulation results show that this adaptive method significantly outperforms a fixed control method. © 2011 Springer-Verlag.

Reduced attentional capacity, but normal processing speed and shifting of attention in developmental dyslexia: evidence from a serial task

We report the performance of a group of adult dyslexics and matched controls in an array-matching task where two strings of either consonants or symbols are presented side by side and have to be judged to be the same or different. The arrays may differ either in the order or identity of two adjacent characters. This task does not require naming – which has been argued to be the cause of dyslexics’ difficulty in processing visual arrays – but, instead, has a strong serial component as demonstrated by the fact that, in both groups, Reaction times (RTs) increase monotonically with position of a mismatch. The dyslexics are clearly impaired in all conditions and performance in the identity conditions predicts performance across orthographic tasks even after age, performance IQ and phonology are partialled out. Moreover, the shapes of serial position curves are revealing of the underlying impairment. In the dyslexics, RTs increase with position at the same rate as in the controls (lines are parallel) ruling out reduced processing speed or difficulties in shifting attention. Instead, error rates show a catastrophic increase for positions which are either searched later or more subject to interference. These results are consistent with a reduction in the attentional capacity needed in a serial task to bind together identity and positional information. This capacity is best seen as a reduction in the number of spotlights into which attention can be split to process information at different locations rather than as a more generic reduction of resources which would also affect processing the details of single objects.

Evaluating the Capacity of Phase Modulator-Controlled Long-Haul Soliton Transmission

We review recent developments in the use of optical solitons for communication systems spanning transoceanic distances. The implementation of "soliton control" to alleviate the detrimental impact of effects such as amplifier noise is shown to be critical for obtaining advantages over competing technologies. The potential performance of two control strategies, namely straight line filtering and synchronous phase modulation, is examined in detail. Design diagrams are used to determine the maximum permissible amplifier spacing, which is a key determinant of system economics. To focus the enquiry, two example system spans are taken, representing transatlantic and transpacific distances. It is concluded that straight line filtering provides very little improvement over a basic design without control. However synchronous phase modulation, which may be implemented using a handful of actively driven components, provides very substantial benefits. These may be used either to extend the overall bit-rate-distance product of the system or to increase the amplifier spacing at more moderate capacities. © 1995 Academic Press. All rights reserved.

Regeneration limit of classical Shannon capacity

Since Shannon derived the seminal formula for the capacity of the additive linear white Gaussian noise channel, it has commonly been interpreted as the ultimate limit of error-free information transmission rate. However, the capacity above the corresponding linear channel limit can be achieved when noise is suppressed using nonlinear elements; that is, the regenerative function not available in linear systems. Regeneration is a fundamental concept that extends from biology to optical communications. All-optical regeneration of coherent signal has attracted particular attention. Surprisingly, the quantitative impact of regeneration on the Shannon capacity has remained unstudied. Here we propose a new method of designing regenerative transmission systems with capacity that is higher than the corresponding linear channel, and illustrate it by proposing application of the Fourier transform for efficient regeneration of multilevel multidimensional signals. The regenerative Shannon limit -the upper bound of regeneration efficiency -is derived. © 2014 Macmillan Publishers Limited. All rights reserved.

Shannon capacity of nonlinear communication channels

The exponentially increasing demand on operational data rate has been met with technological advances in telecommunication systems such as advanced multilevel and multidimensional modulation formats, fast signal processing, and research into new different media for signal transmission. Since the current communication channels are essentially nonlinear, estimation of the Shannon capacity for modern nonlinear communication channels is required. This PhD research project has targeted the study of the capacity limits of different nonlinear communication channels with a view to enable a significant enhancement in the data rate of the currently deployed fiber networks. In the current study, a theoretical framework for calculating the Shannon capacity of nonlinear regenerative channels has been developed and illustrated on the example of the proposed here regenerative Fourier transform (RFT). Moreover, the maximum gain in Shannon capacity due to regeneration (that is, the Shannon capacity of a system with ideal regenerators – the upper bound on capacity for all regenerative schemes) is calculated analytically. Thus, we derived a regenerative limit to which the capacity of any regenerative system can be compared, as analogue of the seminal linear Shannon limit. A general optimization scheme (regenerative mapping) has been introduced and demonstrated on systems with different regenerative elements: phase sensitive amplifiers and the proposed here multilevel regenerative schemes: the regenerative Fourier transform and the coupled nonlinear loop mirror.

ACARS:adaptive context - aware rate selection for DSRC in vehicular networks

Throughput plays a vital role for data transfer in Vehicular Networks which is useful for both safety and non-safety applications. An algorithm that adapts to mobile environment by using Context information has been proposed in this paper. Since one of the problems of existing rate adaptation algorithm is underutilization of link capacity in Vehicular environments, we have demonstrated that in wireless and mobile environments, vehicles can adapt to high mobility link condition and still perform better due to regular vehicles that will be out of communication range due to range checking and then de-congest the network thereby making the system perform better since fewer vehicles will contend for network resources. In this paper, we have design, implement and analyze ACARS, a more robust algorithm with significant increase in throughput performance and energy efficiency in the mist of high mobility of vehicles.