500 research outputs found
Trade Study Analysis for TNS Tokamaks.
A series of parametric trade studies was performed to consistently evaluate the relative.costs and performance parameters of D-T burning tokamaks over a range of plasma sizes and toroidal field (TF) coil technologies. Four different types of TF coil technologies were investigated: water-cooled copper coils, superconducting NbTi and Nb{sub 3}Sn coils, and a "hybrid" coil arrangement consisting of a· normal conducting Cu coil nested within a superconducting NbTi coil. Results of the analysis indicate for TNS operation, for example, that for a given plasma beta at ignition, the Cu TF coil devices are least expensive, followed by the Nb{sub 3}Sn, NbTi, and NbTi/Cu options. Other conclusions and trends resulting from the study are presented and analyzed
Interactions of fishes with particular reference to coelacanths in the canyons at Sodwana Bay and the St. Lucia Protected Area of South Africa
The deep demersal fish fauna at depths of 100–400min canyons off
the St Lucia Marine Protected Area along the north coast of
KwaZulu-Natal is compared with similar fish communities at the
Comoro Islands and in the Indo-Pacific region. Fifty-four fish
species were seen or photographed from the submersible Jago or
by the discovery team of scuba divers in the coelacanth, Latimeria
chalumnae, habitat of the canyons off Sodwana Bay. An additional
94 fish species known from depths of 100–200 m along the coast of
northern KwaZulu-Natal are likely to occur in the canyon habitat.
The fish fauna of the Sodwana canyons shares at least 18 species
with the deep demersal fish community off tropical coral reefs of the
Indo-Pacific region. Thirty-seven of the Sodwana canyon fishes are
also known from the coelacanth habitat in the Comoros
The South African coelacanths - an account on what is known after three submersible expeditions
Using the manned submersible Jago, the habits, distribution and number of coelacanths within all main submarine canyons of the Greater St Lucia Wetland Park were studied during 47 survey dives, with a total bottom time of 166 hours at depths ranging from 46 to 359 m, between 2002 and 2004. Twenty-four individuals were positively identified from three of the canyons, primarily from inside caves at or close to the canyon edges at depths of 96-133 m with water temperatures between 16 and 22.5oC. The population size of coelacanths within the canyons is assumed to be relatively small; coelacanths are resident but not widespread nor abundant within the park
How do supply chain management and information systems practices influence operational performance?:Evidence from emerging country SMEs
This study first provides a comparative analysis of the impact of supply chain management (SCM) and information systems (IS) practices on operational performance (OPER) of small- and medium-sized enterprises (SMEs) operating in two neighbouring emerging country markets of Turkey and Bulgaria. Then, we investigate moderating effects of both SCM–IS-linked enablers and inhibitors on the links between SCM and IS practices and OPER of SMEs. To this end, we first empirically identify the underlying dimensions of SCM and IS practices, and SCM–IS-related enabling and inhibiting factors. Second, a series of regression analyses are undertaken to estimate the impact of the study's constructs on OPER of SMEs. The results are discussed comparatively within the contexts of both Turkish and Bulgarian SMEs and beyond. The study makes a significant contribution to the extant literature through obtaining and analysing cross-national survey data of SCM and IS practices in emerging country markets
The asymptotic iteration method for the angular spheroidal eigenvalues with arbitrary complex size parameter c
The asymptotic iteration method is applied, to calculate the angular
spheroidal eigenvalues with arbitrary complex size
parameter . It is shown that, the obtained numerical results of
are all in excellent agreement with the available
published data over the full range of parameter values , , and .
Some representative values of for large real are
also given.Comment: 15 pages, 1 figur
A standardised ecosystem services framework for the deep sea
Despite its remoteness, human activity has impacted the deep sea and changes to the structure and function of deep-sea ecosystems are already noticeable. In terrestrial and shallow water marine environments, demonstrating how ecosystems support human well-being has been instrumental in setting policy and management objectives for sustainable resource use. Foundational to this approach is a framework of ecosystem service (ES) classification and a synthesis of the knowledge base, which can then be used to structure decision-support tools such as ecosystem accounts or Environmental Impact Assessments. At present, no such framework exists for the deep sea. There is thus an urgent need to determine and assess the ES provided by deep-sea habitats and species before (potentially irreversible) decisions are made about deep-sea habitat use and governance. As a first step towards the incorporation of ES in such decision-making, we undertake two systematic reviews of the scientific literature based on the principles of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) systematic process. This was to define a comparative ES framework and synthesise the current evidence base for how deep-sea habitats support ecosystem services. Our framework proposes four supporting services, three regulating services, four provisioning services and three cultural services for which there is an established and growing body of evidence for the role of deep-sea habitats. The ES framework presented here provides a structure for deep-sea ecosystem services. In its next phase of development, this could provide the foundation for the development of habitat-ecosystem service matrices, which are a critical component for truly accounting for ES in decision-making, particularly spatial management. This framework has significant implications for deep-sea management, conservation and policy, as it provides an ecosystem services-based tool that can be used in any deep-sea ecosystems management across the planet, and it also shows how critical these data gaps are for today’s decisions and how seriously they should be considered in decision-making processes
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Trade Study Analysis for TNS Tokamaks.
A series of parametric trade studies was performed to consistently evaluate the relative.costs and performance parameters of D-T burning tokamaks over a range of plasma sizes and toroidal field (TF) coil technologies. Four different types of TF coil technologies were investigated: water-cooled copper coils, superconducting NbTi and Nb{sub 3}Sn coils, and a "hybrid" coil arrangement consisting of a· normal conducting Cu coil nested within a superconducting NbTi coil. Results of the analysis indicate for TNS operation, for example, that for a given plasma beta at ignition, the Cu TF coil devices are least expensive, followed by the Nb{sub 3}Sn, NbTi, and NbTi/Cu options. Other conclusions and trends resulting from the study are presented and analyzed
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Research Experiences for Teachers in Sensor Networks
This report discusses research on applications of logic flowcharting with a focus in autonomous robotic operations. This research project is part of Research Experiences for Teachers (RET) in Sensor Networks, a National Science Foundation (NSF) funded grant project
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Mass Balance: A Key to Advancing Monitored and Enhanced Attenuation for Chlorinated Solvents
Monitored natural attenuation (MNA) and enhanced attenuation (EA) are two environmental management strategies that rely on a variety of attenuation processes to degrade or immobilize contaminants and are implemented at appropriate sites by demonstrating that contaminant plumes have low risk and are stable or shrinking. The concept of a mass balance between the loading and attenuation of contaminants in a groundwater system is a powerful framework for conceptualizing and documenting the relative stability of a contaminant plume. As a result, this concept has significant potential to support appropriate implementation of monitored natural attenuation (MNA) and enhanced attenuation (EA). For mass balance to be useful in engineering practice, however, it is necessary to quantify it in practical ways that facilitate overall site remediation and which are consistent with existing regulatory guidance. Two divergent philosophies exist for quantifying plume stability--empirical and deterministic. The first relies on historical contaminant concentration data and bulk geochemical information from a monitoring well network and documents plume stability using trend analysis and statistical tools. This empirical approach, when feasible, provides powerful and compelling documentation of plume behavior and mass balance. It provides an interpretation on a relevant scale under field conditions. It integrates the operative attenuation processes measured by observing their actual impact on the plume. The power of the empirical approach was recognized early in the development of MNA guidance and protocols and it is currently the basis of the three lines of evidence used in MNA studies. The empirical approach has some weaknesses, however. It requires a relatively long period of undisturbed historical data. Thus it cannot be effectively applied to sites where active remediation was initiated quickly and is currently operating. It cannot be used as a tool to determine how much source removal is needed or when to turn off active remediation and transition to MNA. It cannot be used to evaluate potential enhancement options (unless a long period of post enhancement monitoring is planned). It provides only indirect information about process and treats the plume as a ''black box''. The empirical approach has the advantage that, when sufficient monitoring data are available, the attenuation capacity can be defined inexpensively and with a high degree of certainty. Alternatively, a deterministic approach can be used to assess mass balance and plume stability. In this approach, the physical, chemical, and biological attenuation processes are used to assess contaminant loading and attenuation. The deterministic approach has the advantage that, when sufficient hydrologic, geochemical, and microbiological data are available, it is possible to project how a system will respond to contaminant removal actions or enhancements of natural attenuation processes. The ''black box'' of the plume is taken apart, quantified, and put back together again. The disadvantage of the deterministic approach is that it is difficult to measure all or most of the relevant hydrologic, geochemical, and biological parameters with any certainty. Case studies over the past decade demonstrate that empirical and deterministic approaches to MNA/EA are not mutually exclusive. These studies document that improved decision support and efficiency result by combining these methods based on the individual challenges presented by a given site. Whenever possible, the empirical approach is used to quantify mass loading and attenuation capacity (mass of contaminant/unit time) at particular sites. This is the most effective way to demonstrate the efficiency of ongoing natural attenuation processes in accordance with current regulatory guidance. But in addition, the monitoring well networks needed to apply the empirical approach can also yield estimates of the hydrologic, geochemical, and biological parameters needed to apply deterministic models. These models can then be used to estimate how contaminant behavior will change over time, as contaminant mass is removed, or if attenuation mechanisms are enhanced by engineering methods. The dual use of these empirical and deterministic approaches can help integrate the use of MNA and EA for overall site remediation
Practical actions to strengthen capacity for deep-water research in Africa
While Africa's deep marine biodiversity offers economic prospects it also supports crucial ecosystem services and sustainable development is dependent on knowledge of these systems. Building understanding of deep-water ecosystems is key, but there are substantial discrepancies in countries' abilities to achieve this. Coinciding with the 2024 Ocean Decade Conference, the Challenger 150 African Network of Deep-water Researchers is pleased to release a report on “Practical Actions to Strengthen Capacity for Deep-water Research in Africa”. Through a series of online workshops, the ANDR brought together 98 individuals from 19 African nations to discuss challenges for deep-water research in Africa, identify solutions to overcome these and propose practical actions going forward
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