Single Supply Source Research Articles

Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers

The petro-archaeometric study of ceramics from the Rittatore excavations, Bec Berciassa archaeological site, was carried out on pottery sherds attributed to an older phase dating back to the Late Bronze Age. This collection represents a small sampling of pottery and the chronology of most of this material is homogeneously ascribable to a period between the 6th and the beginning of the 4th century BC (Iron Age). In addition to the archaeometric study, a geological survey highlighted the resources of the area potentially useful for the development of prehistoric communities, including resources that could be used for ceramic production. A thin section study under optical microscope distinguished five ceramic mixtures. They are mostly coarse-grained, hiatal, and serial-textured, calibrated with the addition of fillers. The fine matrix is homogeneous in composition, although with compositional variations in Fe2O3. Therefore, it is possible to hypothesise a single source of supply. The different types of filler can be traced back to minerals and rocks found outcropping within the basins of the Gesso and Vermenagna rivers and thus potentially present as pebbles in their beds. Calc-schists, sparitic calcite, magmatic rocks (granites and aplites), and sericite-schists have been used since the Bronze Age; quartz sandstones and quartzites are only present in Iron Age pottery. At a macroscopic level, all these filler agents are light in colour, tending to white, almost as if the colour and homogeneity of the geological material were a criterion of choice dictated more by tradition and know-how rather than by any particular technological choice.

Impact of covid-19 on supply chain management in construction industry in Kashmir

The building industry has become a critical economic sector for country’s development. Due to covid-19, world’s most industrialised countries saw significant declines in their GDP. An effective supply chain system ensures higher efficiency rates, better customer relationship and service, reduced production costs and an overall improvement in the financial performance of a construction company. The entry of covid-19 in Kashmir has adversely impacted the supply chain of construction industry and the economy. So, there is a need to mitigate the impact of covid-19 pandemic on the supply chain management for the better future of construction industry. The aim of this paper is to capture the issues, challenges and implications of the covid-19 pandemic on supply-chain activities in Kashmir, India. This also provides strategies and insights on mitigating the risks and impact of the pandemic on supply chain management. Based on the issues identified, a questionnaire survey was conducted to assess the impact of these factors on supply chain management. Exploratory factor analysis and structural equation modelling was used to analyse the factors. The problematic causes include reduction in supply chain flexibility and difficulties in supply chain collaboration. There is a need to diversify the supply chains and avoid the single source of supply.

Applied Magnetism: A Supply-Driven Materials Challenge

Permanent magnets are important in many green energy technologies including wind turbine generators and hybrid-electric vehicle motors. For these applications, volume and weight are important factors driving the overall design, and therefore a high energy density, or energy product, is an important figure of merit. This quantity defines the magnetic energy contained in a given volume of material, and so higher energy density magnets enable smaller, lighter applications. Currently, the most powerful magnets suitable for commercial purposes contain rare earth elements (REE), usually neodymium and dysprosium in the neodymium-iron-boride class of magnets. However, for select applications, often requiring high temperatures, samarium cobalt is the alloy of choice. These magnets have energy densities several times greater than their nearest non-REE-based competitor, which for some applications is the defining factor in creating a viable device. The global supply of these REE is overwhelmingly produced in China, which in 2015 mined more than ten times as much as the next largest producer (Australia). Such market domination effectively creates a single source of supply, leaving industries which rely on REE consumption susceptible to price shocks and supply disruptions of these critical materials. Furthermore, this supply sensitivity may act as a drag on the adaptationmore » rate of green energy technologies, particularly for large-scale users.« less

Optimal pipe-sizing problem of tree-shaped gas distribution networks

This study addresses the optimal pipe-sizing problem of a tree-shaped gas distribution network with a single supply source. An algorithm was developed with the aim of minimizing the investment for constructing a gas distribution network with a tree-shaped layout in which demands are fixed.The construction cost is known to depend on the pipe diameters used for each arc in the network. However, under the assumption that pipe diameters are continuous, we prove that it is possible to obtain the minimum construction cost directly and analytically by an iterating procedure that converts the original tree into a single equivalent arc. In addition, we also show that expanding the converted single arc inversely to the original tree computes the optimal continuous pipe diameter for each arc. Following this, we present an additional heuristic to convert optimal continuous pipe diameters into approximate discrete pipe diameters.The algorithms were evaluated by applying them to sample networks. The numerical results obtained by comparing the approximate discrete diameters with the optimal discrete diameters confirm the efficiency of our algorithms, thereby demonstrating their suitability for designing real gas distribution networks.

Vulnerability assessment of the European natural gas supply

As indigenous natural gas reserves within the European Union (EU) decline, higher gas imports are expected in order to meet future EU gas demand. Natural gas will be transported across considerable distances from regions of gas reserves to European consumers. This raises security of gas supply concerns especially for EU countries that depend heavily on a single supply source or major transit route. A linear programming model of the European gas supplies was developed and used to investigate the impact of loss of the Ukraine transit capacity on gas supply from Russia to Europe. Two demand scenarios – that is a reference case and a high demand case in the winter of 2014/2015 were investigated. The results have shown that gas flows on interconnectors and from storage and liquefied natural gas import terminals compensated for the supply shortfall. Furthermore, to mitigate the effect of the supply shortage, the impact of increasing the capacities of selected pipelines within the EU was compared against increasing the maximum storage withdrawal rates in southeast Europe. Higher storage withdrawal rates achieved lower demand curtailment than the additional interconnector capacity in both scenarios.

LQ optimal and reaching law-based sliding modes for inventory management systems

In this article, the theory of discrete sliding-mode control is used to design new supply strategies for periodic-review inventory systems. In the considered systems, the stock used to fulfil an unknown, time-varying demand can be replenished from a single supply source or from multiple suppliers procuring orders with different delays. The proposed strategies guarantee that demand is always entirely satisfied from the on-hand stock (yielding the maximum service level), and the warehouse capacity is not exceeded (which eliminates the cost of emergency storage). In contrast to the classical, stochastic approaches, in this article, we focus on optimising the inventory system dynamics. The parameters of the first control strategy are selected by minimising a quadratic cost functional. Next, it is shown how the system dynamical performance can be improved by applying the concept of a reaching law with the appropriately adjusted reaching phase. The stable, nonoscillatory behaviour of the closed-loop system is demonstrated and the properties of the designed controllers are discussed and strictly proved.

Health Care Logistics Response in a Disaster

Logistics operations are interwoven among the very fabric of emergency management and no aspect of a health care organization's business processes goes untouched by tenable supply chain management. The purpose of this work is to provide lessons observed during a response and recovery scenario resultant of a snow avalanche that occurred in Afghanistan north of Kabul. The lessons documented throughout this work are specific to how Soldiers, while deployed in support of Operation Enduring Freedom, were faced with one of the most unlikely of scenarios conceivable -- responding to a natural disaster. In this work are observations, relayed by organization-level leadership during a deliberate After Action Review (AAR) related to communications, preparedness, warehouse security, the development of cross-functional teams, the adherence by clinical teams to a single source of supply, equipment and supply accountability, and the development of appropriate pre-configured push packs to support future scenarios such as the one experienced on February 9, 2010.

Induction Machine/Syn-Rel Two-Motor Five-Phase Series-Connected Drive

Multimotor drives, based on utilization of multiphase machines, have been proposed recently. Independent vector control of all the machines of the group can be achieved while using a single multiphase voltage source inverter supply, provided that the stator windings are connected in series in an appropriate manner. The concept is applicable to any system phase number greater than or equal to five. Detailed theoretical and simulation studies have been reported for multiphase multimotor drive configurations of this type and it has been suggested that the concept is valid regardless of the type of ac machines. This paper examines operation of such a drive system when a five-phase induction machine is connected in series with a five-phase synchronous reluctance machine and provides detailed experimental verification of the possibility of independent control of the two-motor drive comprising five-phase motors of different types. The operating principles of the drive system are at first reviewed and a brief description of the experimental system is then given. An extensive presentation of experimental results, collected from a laboratory setup, is further provided. It is shown that fully independent and decoupled vector control of the two machines results, although a single supply source is used.

A Series-Connected Two-Motor Six-Phase Drive With Induction and Permanent Magnet Machines

A novel concept for multimotor drives, based on utilization of multiphase machines, has been proposed recently. Independent vector control of all the machines of the group can be achieved while using a single multiphase inverter supply, provided that the stator windings are connected in series in an appropriate manner. One specific case of such a drive system is a two-motor drive, comprising a symmetrical six-phase machine connected in series with a three-phase machine. The group is supplied from a six-phase current-controlled voltage source inverter (VSI). The available considerations related to this two-motor drive system, consisting of two induction motors, are currently of purely theoretical nature, with the proof-of-concept provided by simulation only. This paper analyzes series-connected two-motor six-phase drive, comprising a six-phase symmetrical induction machine and a three-phase permanent magnet synchronous machine (PMSM) and provides, for the first time, detailed experimental verification of the possibility of independent control of the two motors. The operating principles of the drive system are at first reviewed and a brief description of the experimental system is then given. The emphasis is placed on an extensive presentation of experimental results, collected from a laboratory setup. It is shown that a truly independent and decoupled vector control of the two machines results, although a single supply source is used. The two-motor drive system of the proposed structure is seen as a potentially viable industrial solution for applications requiring one high-power and one low-power machine.

Is there really any duplication in Europe's space activities?

At a time of declining space budgets in Europe, and of a consequent need to make savings, accusations of wasteful duplication—resulting from the large number of national agencies pursuing programmes alongside ESA—are rife, as are calls for the space industry further to consolidate. This viewpoint argues that duplication is not really the issue, however, since most national agencies have become specialists in particular fields. Nor would industry restructuring be straightforward, given the fact that Europe cannot be satisfied with a single source of supply. What is needed is better coordination between space agencies upstream to avoid later duplication, as is now being pursued through ESA's ‘harmonisation process’. The move to create a Network of Centres could also promote worthwhile collective action. These initiatives are more realistic than the technocratic aim of completely restructuring European space.

Cost-parametric analysis of lateral transshipment policies in two-echelon supply chains

In this paper, we examine the cost effects of two lateral (intra-echelon) transshipment approaches in a two-echelon supply chain network, with a single supply source at the higher echelon and multiple retail locations at the lower, through a series of simulation experiments under different operating conditions. An important finding is that either of the proposed lateral shipment approaches is considerably superior to a policy of no such shipments, albeit at the expense of increased transportation activity. Further, an ad hoc emergency transshipment approach appears to be significantly more effective in terms of several important criteria, as compared to a more systematic transshipment technique based on stock level equalization.

Monograph Interlending for the Higher Education Research Community

1. This report was commissioned by CURL (the Consortium of University Research Libraries) with the support of the British Library Cooperation and Partnership Programme in order to recommend the best UK wide monograph interlending infrastructure and associated business model for the higher education research community for the next ten years. The report does not consider the interlending needs of other sectors (for example, public libraries), but its recommendations are unlikely to have adverse implications for them. 2. The report estimates that for 2001-2002 the overall total of interlending requests initiated by the UK higher education sector was approximately 325,000. Of these some 90% (295,000) were estimated to have been successfully completed, of which approximately 79% were supplied by the British Library Document Supply Centre (BLDSC), which holds the most dominant position in the UK monograph interlending system. In addition to the BLDSC there are a number of other providers to whom higher education libraries typically turn if the BLDSC cannot supply an item, but the overall volume of such loans is low. 3. The current monograph interlending system based on the BLDSC has several important strengths: first and most importantly, it works, and has done so successfully for many years. The system is well understood by researchers, is valued by them, and as our own data demonstrates has the support of all CURL libraries. The overall performance of the BLDSC is high in terms of speed of delivery and other operational benchmarks, and also represents good value for money for the sector as a whole. Studies undertaken for the Research Support Libraries Group (RSLG) estimated the savings achieved through all forms of central document supply to be between £45 and £50 million. In relation to individual loan charges an email survey of CURL libraries suggested that although those responding welcomed the cheaper options provided by some other providers, the charges of the BLDSC were accepted as being at least satisfactory. 4. The current system has no major weaknesses, however significant concerns exist about whether it can be sustained in the future without change. The current interlending system is likely to come under increasing strain because of: declining investment in loan stock unless more collaborative approaches to acquisition take place; an increase in the diversity of lending provision as libraries struggle to meet the needs of their own researchers in the context of a declining central fill rate; and specific difficulties concerning the loan of items from special collections. These concerns are part of the broader issue of the future of library resources which is addressed in the RSLG report. 5. If such developments were allowed to occur, they would lead to the loss of many of the advantages of centralisation that now exist, and involve interlending librarians spending much more time trying to source material. Rather we see the opposite as desirable: obtaining maximum benefit through a suitably run single source of supply, with as much requesting and distribution as possible done electronically. The RSLG has made it clear that a gradual deterioration in resource availability for research use should not be accepted, and our conclusion is that the same principle should apply to document supply and loans. 6. The report considers nine wide-ranging options for revising the current interlending system, and seeks to build upon existing strengths. Each option is tested against six key criteria: ○ It should enable the current fill rate in higher education libraries of approximately 90% to be maintained, and if possible improved. ○ It should operate to performance standards not lower than those currently achieved by the BLDSC. ○ It should maximise value for money in relation to collection development, procurement, and in other related areas.

A simulation study of lateral shipments in single supplier, multiple buyers supply chain networks

This study examines the effects, in terms of some selected criteria, of two lateral (intra-echelon) transshipment approaches in a two-echelon supply chain network, with a single supply source at the higher echelon and multiple retail locations at the lower, through a series of simulation experiments under different operating conditions. An important finding is that either of the proposed lateral shipment approaches are considerably superior to a policy of no such shipments, albeit at the expense of increased transportation activity. Further, an ad hoc emergency transshipment approach appears to be significantly more effective in terms of several important criteria, as compared to a more systematic transshipment technique based on stock level equalization.

Buffer stock analysis for a single source-single location inventory model with delivery lag

This paper treats a buffer stock inventory system with a single source of supply and a single location of demand. It extends the work of Salameh (1997) by assuming a non-zero lead time and a finite rather than instantaneous delivery. Two cases of deterministic demand are treated: (1) the constant consumption rate case; and (2) the fluctuating demand case. The optimum inventory policy is to determine the buffer stock level that minimizes the sum of the expected holding and inventory stockout costs. Numerical examples are provided to illustrate the solution procedures for the mathematical models developed.

The economics of partnership sourcing versus adversarial competition: a critique

In the strategic procurement management literature two general forms of purchasing arrangement feature—‘partnership sourcing’ and ‘competition’. Usually partnership sourcing is said to be superior because it leads to long-term collaboration based on trust between buyer and supplier. One product is a reduction of the supplier base with firms perhaps relying on a single source of supply or a small number of preferred suppliers. The paper reconsiders procurement methods in terms of a continuum using the economics of transaction costs. The paper then illustrates the economic issues discussed by considering procurement in the defence sector. Defence is taken as an example of public procurement with experience and opportunities for competition, partnership sourcing and long-term buyer-supplier relationships. The paper concludes that the case for partnership sourcing over competition is not clear cut.

The Turkish air force, 1939–45: the rise of a minor power

On 16 June 1938, Sabiha Gokgen, an adopted daughter of Atatiirk, pulled back on the throttle of her American Vultee V-11 attack bomber, lifted off from Yesilk6y airfield near Istanbul, and headed for Athens. Thus began perhaps the most celebrated demonstration of Turkish air power since the end of the War of Independence in 1922. Gokgen set out on a goodwill flight that took her to Athens, Salonica, Sofia, Belgrade, and Bucharest.1 This flight was meant to symbolize Turkey's political interests in the Balkans as well as its determination to obtain the latest military technology and forge a strong air force to help make it a significant regional power. As the following study will show, it was largely successful. Despite his country's limited resources, Atatiirk did his best to promote the air force, as his daughter's flight shows, before his death on 10 November 1938.2 During the 1930s it grew at a modest pace, expanding from three battalions in 1928, to three regiments in 1932, to three brigades in 1939. The main bases were Eskisehir, Izmir, and Diyarbakir.3 Turkey had attempted to establish a national aircraft industry but with little success. Junkers had started a factory in Kayseri in 1925. It failed and its facilities were leased to the Curtiss-Wright Corporation in the early 1930s. This American company managed to assemble only a few planes.4 Therefore, throughout this decade, and even later (indeed, until coproduction of the F-16 in 1987), virtually all combat aircraft were purchased from abroad: France, Great Britain, Germany, Poland, America, Italy, Czechoslovakia, and the Netherlands.s Although this naturally resulted in difficult maintenance problems, Ankara did not want to be dependent on a single source of supply. On the eve of World War II, the Turkish Air Force (TAF) had approximately 240 planes: bombers, fighters, and trainers, some of which were obsolete.6

Implications of single vs. multiple buying sources

This article explores the viability of an industrial buyer's preference for a single supply source (SSS) versus multiple sources of supply (MSS) as an effective basis of industrial market segmentation. The empirical findings of the study reported here indicate that there are some perceived vendor attributes and organizational characteristics which differentiate between firms that prefer to employ SSS and those that utilize MSS. Managerial implications for industrial marketers and procurement personnel are also discussed.

U.S. Energy relations with the Asia-Pacific region

The goal of the U.S. National Energy Policy is to foster an adequate supply of energy at reasonable costs by promoting a balanced and mixed energy resource system that is not unduly dependent on any single source of supply, either foreign or domestic. Because the world oil market is interdependent, the United States is concerned not only with reducing its own vulnerability to oil and to other energy emergencies, but also with reducing the vulnerability of other countries, such as those in the Asia-Pacific region. To accomplish this the United States can modify its energy and oil use to ensure that Asia-Pacific countries will not be deprived of the energy supplies necessary for growth; it can undertake joint research and development efforts with countries in the region to promote cooperative approaches to mutual energy concerns; and it can cooperate with countries in the region to promote greater exports of U.S. energy resources and to thus provide secure and reliable energy supplies to Asia-Pacific countries.

Investment sequencing, allocation, and learning in the design of water resources systems: An empirical application

Four of the more important unresolved problems in the design of water resources systems involve a determination of methods to deal with technological progress (e.g., new desalting processes), availability of water from more than a single supply source, the rate of investment in the capital complex employed to exploit the resource along with the allocation of water once the capital complex is in place, and price sensitive demands for water. The importance of these issues is demonstrated, and a decision framework is advanced which formally incorporates each along with a new technique for solving large‐scale investment‐sequencing and water allocation problems. The robustness and convergence properties are formally demonstrated. Finally, the framework is applied to an empirical situation in California with rather encouraging results.

An Exploratory Investigation of Brand Switching

Data for this investigation of variables influencing brand switching were obtained in an isolated community in the Midwest where nearly all residents purchased food products from a single source of supply. All residents worked for a single employer, who verified their income levels. This setting provided nearly ideal research conditions.