2,227 research outputs found

    An Analysis of Supplier-Buyer Interdependence and Its Significance to Management in the Control of Product Quality

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    In recognition of management\u27s responsibility for assuring the required quality, timely delivery, and optimum cost of purchased material, this study develops and analyzes a technique for the scientific selection of suppliers. This technique is designed to determine the capability of suppliers to manufacture and deliver material in accordance with the buyer\u27s requirements and specifications. By being able to differentiate between reliable and unreliable sources, the buyer has surmounted a major obstacle to the procurement of uniform product of satisfactory quality and reliability. It is also the purpose of this study to develop and analyze a procedure for controlling supplier performance and assuring effective supplier-buyer relations. This procedure is designed to promote a mutual understanding of the supplier\u27s capabilities and the buyer\u27s requirements as they relate to the co-operative effort and responsibility of producing an acceptable product. The full utilization of a supplier\u27s capabilities, and the assurance of his satisfactory performance are completely dependent upon the ackowledgement and definition of this responsibility and team effort

    Effects of anode material on arcjet performance

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    Anodes fabricated from four different materials were tested in a modular arcjet thruster at 1 kW power level on nitrogen/hydrogen mixtures. A two-percent thoriated tungsten anode served as the control. Graphite was chosen for its ease in fabrication, but experienced severe erosion in the constrictor and diverging side. Hafnium carbide and lanthanum hexaboride were chosen for their low work functions but failed due to thermal stress and reacted with the propellant. When compared to the thoriated tungsten nozzle, thruster performance was significantly lower for the lanthanum hexaboride insert and the graphite nozzle, but was slightly higher for the hafnium carbide nozzle. Both the lanthanum hexaboride and hafnium carbide nozzle operated at higher voltages. An attempt was made to duplicate higher performance hafnium carbide results, but repeated attempts at machining a second anode insert were unsuccessful. Graphite, hafnium carbide, and lanthanum hexaboride do not appear viable anode materials for low power arcjet thrusters

    Factors Affecting Hay Supply and Demand in Tennessee

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    Understanding the interactions between supply and demand for hay is important because of hay’s significance to the agricultural sector and economy, and because hay is an important crop on highly erodible soils. As an example, Tennessee has the most erodible cultivated cropland in the United States (Denton, 2000), nearly half of the state’s current CRP acreage contracts are set to expire in 2007 (U.S. Department of Agriculture, 2006), and hay is one of the most economically important crops produced in the state (U.S. Department of Agriculture, 2004). Cross (1999) attributed the upward trend in Tennessee hay acreage since 1980 to an increasing number of farmers who were searching for alternative production activities, such as hay, pasture and livestock, to replace row crops on erodible soils (U.S. Congress, House of Representatives and Senate, 2002). Hay ranked tenth in value of receipts in Tennessee at 49.25millionin2006andcattleandcalfproductionrankedfirstat49.25 million in 2006 and cattle and calf production ranked first at 500 million. Hay ranked second in value of production at 262millionin2003andaveraged262 million in 2003 and averaged 248 million over a five period from 2002 – 2006. Underscoring the importance of hay in Tennessee was the state’s national ranking of fourth in the production of other hay (excluding alfalfa) at 4.25 million tons in 2006 (U.S. Department of Agriculture, 2007). To quantify these supply and demand relationships, one must understand the characteristics of hay markets. Markets are usually localized because of the weight and bulky physical characteristics of hay. Although hay species are not identical, in many livestock production situations most are close substitutes, with the possible exception of alfalfa hay. In Tennessee, alfalfa is a differentiated hay product used mostly by dairy and equine producers. Nevertheless, alfalfa constituted only 2.5% of all hay produced in Tennessee in 2003 (U.S. Department of Agriculture, 2004) and its price tends to move proportionally with other hay prices; thus, for modeling purposes alfalfa and other hay can be aggregated as in Shumway’s (1983) study of Texas field crops and treated as a composite commodity (Nicholson, 2005) called hay. In 2002, 47,000 operations within the state produced forage, while on the demand side, 50,000 operations were involved in beef and dairy production with another 24,000 equine operations (U.S. Department of Agriculture, 2004). Despite the lack of national and state central markets for hay (Cross, 1999), buyers and sellers seem to be aware of the current prices in their area. Word of mouth, a hay directory website (Tennessee Farm Bureau Federation, 2005), and the Farm Facts bulletin (Tennessee Agricultural Statistics Service, 2004) are among the primary outlets for price discovery (Rawls, September 2004). Hay producers are typically assumed to be price takers (Shumway, 1983) because of the large numbers of sellers and buyers; nevertheless, search costs and price differentials can result from the lack of a central market. Even though hay and livestock producers have avenues for price determination in the short run, they have little information about what causes supply and demand for hay to change from year to year. The overall objective of this research was to illustrate how the understanding of hay markets can provide valuable information to hay and livestock producers and agricultural policymakers. Using the Tennessee hay market as an example, the specific objectives were to: 1) determine the factors that influence Tennessee hay supply and quantify their effects, 2) determine the factors that influence Tennessee hay demand and quantify their effects, and 3) briefly illustrate the importance of hay supply and demand information to policymakers. Estimating factors that influence hay supply and demand can help to provide hay and livestock producers with valuable information for making more informed business decisions and policymakers with insight into how proposed agricultural policies might affect hay and livestock producers. To accomplish the objectives, Tennessee hay supply and demand were modeled econometrically, and the coefficients of the models were used to quantify hay acreage, yield, and price responses to the factors that influence the Tennessee hay market. The results were then used to briefly illustrate the potential impacts on the 2008 Tennessee hay price from the retirement of Conservation Reserve Program (CRP) acreage in 2007. Hay acreage proved to be fairly unresponsive to output and input prices in both the short and long runs. The weak response of hay acreage to own and substitute crop prices may result from many hay producers also being cattle producers that harvest their own hay in an effort to guarantee a reliable supply of roughage to feed their herds throughout the winter months. They might be willing to give up potentially higher profits from a production alternative to avert the risk of feed shortages for their cattle. The hay price appeared to be responsive to real per capita income with a price flexibility of 1.55. This finding is reasonable because an increase in real per capita income results in more purchasing power for a typical household. As purchasing power increases, one would expect beef consumption to increase because beef is a normal good (Schroeder and Mark, 1999). Increased beef consumption would positively influence the derived demand for beef production inputs; hence, increased demand for hay. A weak response of hay price to the quantity of hay produced (HPRODt) could be explained by the hay market structure. First, some livestock farmers may produce large amounts of hay for their own livestock, much of which is not sold on the market. These farmers may be able to produce hay at a lower cost than market price, or they may be willing to forgo the potential cost savings from buying hay from an off-farm source to avert the risk of feed shortages for their cattle. Additionally, unlike the market for corn or cattle, the hay market is much less organized and structured. Farmers producing hay for the cash market have no nearby and convenient grain elevator or auction market at which to sell their product. Weak response to changes in hay quantity and price suggests that hay farmers may not be driven solely by the profit motive. Instead, other motives may also enter into their objective functions as utility maximizers.acreage response, derived demand, elasticities, hay, inverse demand function, price flexibilities, yield response, Crop Production/Industries, Demand and Price Analysis, D,

    Observing IMBH-IMBH Binary Coalescences via Gravitational Radiation

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    Recent numerical simulations have suggested the possibility of forming double intermediate mass black holes (IMBHs) via the collisional runaway scenario in young dense star clusters. The two IMBHs formed would exchange into a common binary shortly after their birth, and quickly inspiral and merge. Since space-borne gravitational wave (GW) observatories such as LISA will be able to see the late phases of their inspiral out to several Gpc, and LIGO will be able to see the merger and ringdown out to similar distances, they represent potentially significant GW sources. In this Letter we estimate the rate at which LISA and LIGO will see their inspiral and merger in young star clusters, and discuss the information that can be extracted from the observations. We find that LISA will likely see tens of IMBH--IMBH inspirals per year, while advanced LIGO could see ~10 merger and ringdown events per year, with both rates strongly dependent on the distribution of cluster masses and densities.Comment: Accepted for publication in ApJL. Minor changes to reflect accepted version. 4 pages in emulateapj, 3 figure

    The development of a position-sensitive CZT detector with orthogonal co-planar anode strips

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    We report on the simulation, construction, and performance of prototype CdZnTe imaging detectors with orthogonal coplanar anode strips. These detectors employ a novel electrode geometry with non-collecting anode strips in one dimension and collecting anode pixels, interconnected in rows, in the orthogonal direction. These detectors retain the spectroscopic and detection efficiency advantages of single carrier (electron) sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N×N array of imaging pixels are with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with 8×8 unit cells (1×1×5 mm3)are compared to the simulations. Results of position and energy resolution measurements are presented and discussed

    Analog processing of signals from a CZT strip detector with orthogonal coplanar anodes

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    We present the requirements, design, and performance of an analog circuit for processing the non-collecting anode strip signals from a cadmium zinc telluride (CZT) strip detector with orthogonal coplanar anodes. Detector signal simulations and measurements with a prototype are used to define the range of signal characteristics as a function of location of the gamma interaction in the detector. The signals from the non- collecting anode strip electrodes are used to define two of the three spatial coordinates including the depth of interaction, the z dimension. Analog signal processing options are discussed. A circuit to process the signals from the non- collecting anode strips and extract from them the depth of interaction is described. The circuit employs a time-over- threshold (TOT) measurement. The performance of the detector prototype with a preliminary version of this circuit is presented, and future development work is outlined

    FORS 440.01: Timber Stand Management / Service Learning

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    Development and Validation of eRADAR: A Tool Using EHR Data to Detect Unrecognized Dementia.

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    ObjectivesEarly recognition of dementia would allow patients and their families to receive care earlier in the disease process, potentially improving care management and patient outcomes, yet nearly half of patients with dementia are undiagnosed. Our aim was to develop and validate an electronic health record (EHR)-based tool to help detect patients with unrecognized dementia (EHR Risk of Alzheimer's and Dementia Assessment Rule [eRADAR]).DesignRetrospective cohort study.SettingKaiser Permanente Washington (KPWA), an integrated healthcare delivery system.ParticipantsA total of 16 665 visits among 4330 participants in the Adult Changes in Thought (ACT) study, who undergo a comprehensive process to detect and diagnose dementia every 2 years and have linked KPWA EHR data, divided into development (70%) and validation (30%) samples.MeasurementsEHR predictors included demographics, medical diagnoses, vital signs, healthcare utilization, and medications within the previous 2 years. Unrecognized dementia was defined as detection in ACT before documentation in the KPWA EHR (ie, lack of dementia or memory loss diagnosis codes or dementia medication fills).ResultsOverall, 1015 ACT visits resulted in a diagnosis of incident dementia, of which 498 (49%) were unrecognized in the KPWA EHR. The final 31-predictor model included markers of dementia-related symptoms (eg, psychosis diagnoses, antidepressant fills), healthcare utilization pattern (eg, emergency department visits), and dementia risk factors (eg, cerebrovascular disease, diabetes). Discrimination was good in the development (C statistic = .78; 95% confidence interval [CI] = .76-.81) and validation (C statistic = .81; 95% CI = .78-.84) samples, and calibration was good based on plots of predicted vs observed risk. If patients with scores in the top 5% were flagged for additional evaluation, we estimate that 1 in 6 would have dementia.ConclusionThe eRADAR tool uses existing EHR data to detect patients with good accuracy who may have unrecognized dementia. J Am Geriatr Soc 68:103-111, 2019

    Progress in the study of CdZnTe strip detectors

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    We report new performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector under study as a prototype imaging spectrometer for astronomical x-ray and gamma-ray observations. The prototype is 1.5 mm thick with 375 micron strip pitch in both the x and y dimensions. Previously reported work included demonstrations of half-pitch spatial resolution (approximately 190 microns) and good energy resolution and spectral uniformity. Strip detector efficiency measurements have also been presented. A model that includes the photon interaction, carrier transport and the electronics was developed that qualitatively reproduced the measurements. The new studies include measurements of the CdZnTe transport properties for this prototype in an effort to resolve quantitative discrepancies between the measurements and the simulations. Measurements of charge signals produced by laser pulses and (alpha) -rays are used to determine these transport properties. These are then used in the model to predict gamma-ray efficiencies that are compared with the data. The imaging performance of the detector is studied by scanned laser and gamma beam spot measurements. The results support the model\u27s prediction of nearly linear sharing of the charge for interactions occurring in the region between electrodes. The potential for strip detectors with spatial resolution much finer than the strip pitch is demonstrated. A new design scheme for strip detectors is shortly discussed
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