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The authors consider parallel four-state tandem open queueing network. The queue capacity is infinite. Passenger arrival rate is Poisson distribution and service rate is exponential distribution. The queue is constructed in the form of tandem queue, and each and every queue of tandem queue is single server (M/M/1) queue. In tandem queue, passengers will leave the system once they receive service from both the states. The purpose of this paper is to provide performance analysis for four-state tandem open queue network, and a governing equation is formulated with the help of transition diagram. Using Burke theorem, the authors formulated equation for average number of passenger in the system, average waiting time of passenger in the system, average number of passenger in the queue and average waiting time of passenger in the queue.

This paper used Burke’s theorem.

In this paper, performance analysis is done for parallel four-state tandem open queueing network and performance measure solved using Burkes theorem formula. K. Sreekanth et al. has done performance analysis for single tandem queue with three states. In this paper, the authors have done performance analysis for two tandem queues parallel with four states. This four-state tandem open queueing network is suitable for real world applications. This paper can extend for more number of service states and multi-server states according to the application, and in such case, the authors have to prove and explain with numerical examples. This analysis is more useful for the applications such as airports, railway stations, bus-stands and banks.

In this paper, parallel four-state tandem open queueing network and performance measure has been solved using Burke’s theorem formula.

I‐V characteristics of GaAs n‐i‐n structures are calculated by considering impact ionization of carriers. Impact ionization at reverse‐biased n‐i junction becomes a cause of steep current rise when an acceptor density in the i‐layer is high. It is shown that an optimum acceptor density exists to keep a good isolation. Photoconduction transients of GaAs n‐i‐n structures are also simulated, and are shown to be strongly affected by existence of n‐i junctions.

This paper seeks to analyze ecological networks from a different viewpoint, using the concepts of orbits, coverage, invariant sets, etc.

A very simple view of ecosystems is presented, without delving into their multiple properties. Specifically, an ecosystem will be considered a system containing living and non‐living entities whose interrelationships include those of predator‐prey and competition. On interpreting that orbits are associated with ecosystems' direct and indirect paths, it is possible to present a much more conceptual design of ecological networks.

An ecosystem's two most important relationships, those of predator‐prey and competition, appear to be interconnected with the concepts of coverage, invariance and orbit, with multiple properties.

There are many interesting analyses of ecological networks' indirect effects that develop the quantitative and qualitative theory of ecological networks. What is new in this study is that it is the first dealing with orbits in the field of ecosystems.

THE use of liquid oxygen as an oxidizer for various fuels in liquid rocket propellent systems is not new. Professor Goddard used liquid oxygen in his rocket experiments and the well known German V‐2 rockets used this material as an oxidizer. However, its effect on non‐metallic materials ordinarily used in rocket systems was not investigated until recent years. This investigation was prompted by phenomena which had been experienced by rocket engine and rocket aircraft manufacturers and by suppliers of the material. It was observed that when some organic materials came in intimate contact with liquid oxygen they became prone to detonation when subjected to certain impact energies. This was undoubtedly due to the formation of unstable organo‐peroxide compounds which when impacted released high levels of energy resulting in an explosion. Specifically, when liquid oxygen was accidently spilled on asphalt and inadvertently stepped on, the asphalt would often explode. Also, leather gaskets immersed in liquid oxygen and subjected to surge impact detonated with disastrous effects.

In the course of development of human communities towards industrially advanced societies of today, there have been changes not only in economic conditions in the majority of fields of human activity but also in the ways of providing for food, which went hand in hand with changes in living conditions. Large‐scale industrial production has brought about major changes in the way of life of the population. The development of industrial agglomerations results in a growing number of city dwellers, most of whom have no chance of producing foodstuffs of their own in kind. The distance between residential and industrial areas has been growing, the number of employed women has risen considerably. These are but a few factors affecting the way of boarding, particularly in households.

In the paper the optimization procedure of a direct current motor with a hybrid excitation has been presented. The excitation system consists of a shunt field winding disposed around field pole and permanent magnet, both acting in parallel. The field distribution in motor for various magnet and field pole dimensions has been determined using finite element method. The flux linkage with the armature winding has been computed. Demagnetizing effect of armature current was taken into account. The optimal permanent magnet and the field pole dimensions, ensuring minimum total cost of purchase and work during assumed period of time were calculated. Motor characteristics e.g. rated torque, rated current, speed regulation limit were used as constraints. In worked up algorithm and computer program Carroll internal penalty function method was used. Some basic suggestions tor design of optimal hybrid excited dc motors with parallel permanent magnet and electromagnetic excitation are given.

This study examined the reciprocal influence of demand learning and preference matching in the context of store brand customization. The demand-learning effect refers to the collection of market demand information through production, based on pre-order demands, enabling retailers to accurately predict and allocate product quantities, thus improving inventory management. The preference-matching effect involves engaging consumers in the production and design processes of store brands to align fully with their preferences, thereby increasing the purchase impact of store brand products and promoting consumption.

We employ game-theoretic models to analyze a two-echelon supply chain consisting of a manufacturer and a retailer. The retailer offers both national brands, manufactured by the supplier and in-house store brands. To enhance their competitive edge, the retailer can adopt a customized strategy targeting the store brand to attract a wider consumer base.

The analysis reveals that, under low commission fees, the manufacturer consistently opts for high production quantities, irrespective of the level of demand uncertainty. However, when the perceived value of a store brand is low and demand uncertainty is either low or high, the retailer should choose a minimal or zero production quantity. The decision-making process is influenced by the customization process, wherein the effects of demand learning and preference matching occasionally mutually reinforce each other. Specifically, when the perceived value of a store brand is low, or the product cost is high, along with high customization costs, the interplay between demand learning and preference matching becomes mutually inhibiting. Consequently, the significance of store brand customization diminishes.

This study enhances the current body of knowledge by providing a deeper understanding of the theoretical value of store brand customization. In addition, it offers valuable decision-making support to enterprises by assisting them in selecting appropriate inventory and customization strategies.

This paper aims to encourage PR practitioners to appreciate their role as the pivot of their organisation’s reputation management. It discusses the importance of codes of ethics, claiming that these should be reviewed by public relations associations every 4‐5 years. Good conduct is essential for every PR practitioner as a reputation manager, and PR associations must ensure that codes of ethics are enforced. PR associations should address the challenge posed by the boom in the labour markets for PR practitioners by ensuring that all practitioners are well trained.

Often, real estate factors are given much of the credit for a particular site’s success or failure when it comes to sales. The current paper asserts that some of the praise or blame heaped onto real estate decision‐makers may be undue. Sometimes success or failure is due to non‐real estate factors such as a marketing or advertising strategy, operations, or brand awareness. The paper discusses non‐real estate variables that contribute to a site’s overall success or failure, and offers diagnostics and suggestions to help address non‐real estate problems that could influence sales.