A Flight Prediction for Performance of the SWAS Solar Array Deployment Mechanism

The focus of this paper is a comparison of ground-based solar array deployment tests with the on-orbit deployment. The discussion includes a summary of the mechanisms involved and the correlation of a dynamics model with ground based test results. Some of the unique characteristics of the mechanisms are explained through the analysis of force and angle data acquired from the test deployments. The correlated dynamics model is then used to predict the performance of the system in its flight application

ENGINEERING COST ESTIMATES FOR PELLETING MINNESOTA SOYBEAN MEAL

Crop Production/Industries,

Realtime Optimization of MPC Setpoints using Time-Varying Extremum Seeking Control for Vapor Compression Machines

Recently, model predictive control (MPC) has received increased attention in the HVAC community, largely due to its ability to systematically manage constraints while optimally regulating signals of interest to setpoints. For example, in a common formulation of an MPC control problem for variable compressor speed vapor compression machines, the setpoints often include the zone temperature and the evaporator superheat temperature. However, the energy consumption of vapor compression systems has been shown to be sensitive to these setpoints. Further, while superheat temperature is often preferred because it can be easily correlated to heat exchanger efficiency (and therefore cycle efficiency), direct measurement of superheat is not always available. Therefore, identifying alternate signals in the control of vapor compression machines that correlate to efficiency is desired. Conventionally, methods for maximizing the energy efficiency rely on the use of mathematical models of the physics of vapor compression systems. These model-based approaches attempt to describe the influence of commanded inputs on the thermodynamic behavior of the system and the consumed electrical energy, and they are used to predict the combination of inputs that both meet the heat load requirements and minimize energy consumption. However, these models of vapor compression systems rely on simplifying assumptions in order to produce a mathematically tractable representation. Further, they are difficult to derive and calibrate, and often do not describe variations over long time scales, such as those due to refrigerant losses or accumulation of debris on the heat exchangers. In this paper, we consider a model-free extremum seeking algorithm that adjusts setpoints provided to a model predictive controller. While perturbation-based extremum seeking methods have been known for some time, they suffer from slow convergence rates---a problem emphasized by the long time constants associated with thermal systems. Our method uses a new algorithm (time-varying extremum seeking), which has dramatically faster and more reliable convergence properties. In particular, we regulate the compressor discharge temperature using an MPC controller with setpoints selected from a model-free time-varying extremum seeking algorithm. We show that the relationship between compressor discharge temperature and power consumption is convex (a requirement for this class of realtime optimization), and use time-varying extremum seeking to drive these setpoints to values that minimize power. The results are compared to the traditional perturbation-based extremum seeking approach. Further, because the required cooling capacity (and therefore compressor speed) is a function of measured and unmeasured disturbances, the optimal compressor discharge temperature setpoint must vary according to these conditions. We show that the energy optimal discharge temperature is tracked with the time-varying extremum seeking algorithm in the presence of disturbances

High sensitivity of 17O NMR to p-d hybridization in transition metal perovskites: first principles calculations of large anisotropic chemical shielding

A first principles embedded cluster approach is used to calculate O chemical shielding tensors, sigma, in prototypical transition metal oxide ABO_3 perovskite crystals. Our principal findings are 1) a large anisotropy of sigma between deshielded sigma_x ~ sigma_y and shielded sigma_z components (z along the Ti-O bond); 2) a nearly linear variation, across all the systems studied, of the isotropic sigma_iso and uniaxial sigma_ax components, as a function of the B-O-B bond asymmetry. We show that the anisotropy and linear variation arise from large paramagnetic contributions to sigma_x and sigma_y due to virtual transitions between O(2p) and unoccupied B(nd) states. The calculated isotropic delta_iso and uniaxial delta_ax chemical shifts are in good agreement with recent BaTiO_3 and SrTiO_3 single crystal 17O NMR measurements. In PbTiO_3 and PbZrO_3, calculated delta_iso are also in good agreement with NMR powder spectrum measurements. In PbZrO_3, delta_iso calculations of the five chemically distinct sites indicate a correction of the experimental assignments. The strong dependence of sigma on covalent O(2p)-B(nd) interactions seen in our calculations indicates that 17O NMR spectroscopy, coupled with first principles calculations, can be an especially useful tool to study the local structure in complex perovskite alloys.Comment: 12 pages, 3 figures, and 3 Table

Statistical mechanics of Floquet systems: the pervasive problem of near degeneracies

The statistical mechanics of periodically driven ("Floquet") systems in contact with a heat bath exhibits some radical differences from the traditional statistical mechanics of undriven systems. In Floquet systems all quasienergies can be placed in a finite frequency interval, and the number of near degeneracies in this interval grows without limit as the dimension N of the Hilbert space increases. This leads to pathologies, including drastic changes in the Floquet states, as N increases. In earlier work these difficulties were put aside by fixing N, while taking the coupling to the bath to be smaller than any quasienergy difference. This led to a simple explicit theory for the reduced density matrix, but with some major differences from the usual time independent statistical mechanics. We show that, for weak but finite coupling between system and heat bath, the accuracy of a calculation within the truncated Hilbert space spanned by the N lowest energy eigenstates of the undriven system is limited, as N increases indefinitely, only by the usual neglect of bath memory effects within the Born and Markov approximations. As we seek higher accuracy by increasing N, we inevitably encounter quasienergy differences smaller than the system-bath coupling. We therefore derive the steady state reduced density matrix without restriction on the size of quasienergy splittings. In general, it is no longer diagonal in the Floquet states. We analyze, in particular, the behavior near a weakly avoided crossing, where quasienergy near degeneracies routinely appear. The explicit form of our results for the denisty matrix gives a consistent prescription for the statistical mechanics for many periodically driven systems with N infinite, in spite of the Floquet state pathologies.Comment: 31 pages, 3 figure

Critical Analysis of Talent Management Strategies on Medical Employees Retention in Public Hospitals in Kenya: A Case of Kenyatta National Hospital

Hiring a qualified and talented workforce and implementing a program to retain these employees is a key component to successful workforce retention. However, one of the challenges of managers in today`s health sector in Kenya lies in building a workplace of choice where employees want to remain for a long time. Any employer`s foremost responsibility is retention of the best employees, and this can only be achieved by managing employee talent well to keep them satisfied and motivated. The purpose of this paper was to analyze various programs of managing medical personnel’s talent in the public hospitals in Kenya, a case of Kenyatta national hospital. The research objectives elaborated the independent variables which were: Availability of career development opportunities, nature of the workplace climate and learning, levels of training and development opportunities available, and attractiveness of compensation and benefits. These independent variables were assumed to have significant relationships with the dependent variable which was employee retention. Theoretical framework focused on the social exchange theory, cognitive career theory and Hertzberg`s motivation- hygiene theory. The total population of the study comprised of a total 800 medical doctors and nurses who have been in the service for less than five years and over five years at the Kenyatta national hospital Nairobi, Kenya. The study derived a sample size of eighty (80), arrived at by calculating 10% of the study population. The study`s sampling technique that was used was judgemental sampling. The study used mixed methods of data collection. Mean and standard deviation was calculated in data analysis. Regression analysis model was used to determine the relationship between the dependent and the independent variables. This was done using the statistical package for social studies software (SPSS) version 21. Keywords: Talent management, medical employee, employee retention, Kenyatta national hospita

Erlös von Körnerleguminosen als Speiseware im oberösterreichischen Alpenvorland unter Bedingungen der biologischen Landwirtschaft

Körnerleguminosen enthalten in ihren Samen einen hohen Proteingehalt und können so ausgezeichnet zu einer ressourcenschonenden, eiweißreichen und gesunden Ernährungsweise beitragen. Im vorliegenden Versuch wurden sechs Speise-Körnerleguminosen in einem Feldversuch am Versuchsstandort Lambach /Stadl-Paura auf ihre Anbaueignung im oberösterreichischen Alpenvorland getestet. Deckungsbeiträge wurden errechnet. Bei einem Preis von 1,90 € kg-1 sind sehr hohe Deckungsbeiträge – bis zu 2300 € ha-1 für die Trockenbohne „Black Turtle“ – möglich. Der Versuch zeigte, dass es im humiden Alpenvorland möglich ist, Körnerleguminosen für Speisezwecke anzubauen, und dass sich ihr Anbau für LandwirtInnen als interessante Option erweisen kann

Development of a direct match technique for star identification on the SWAS mission

A direct match technique for star identification was developed for use with the star tracker on the SWAS (Submillimeter Wave Astronomy Satellite) spacecraft. In this technique, tracker searches are used in a two-step process for an implicit direct match star identification. A simulation of the star acquisition process was created and used in the preparation of guide star selection requirements. Flight software implementing this star acquisition technique has been developed and tested

Effects of Estuary-Wide Seagrass Loss on Fish Populations

Globally, habitat loss in coastal marine systems is a major driver of species decline, and estuaries are particularly susceptible to loss. Along the United States Pacific coast, monospecific eelgrass (Zostera marina) beds form the major estuarine vegetated habitat. In Morro Bay, California, eelgrass experienced an unprecedented decline of \u3e 95%, from 139 ha in 2007 to \u3c 6 ha by 2017. Fish populations were compared before and after the eelgrass decline using trawl surveys. Beach seines surveys were also conducted during the post-decline period to characterize species within and outside of remnant eelgrass beds.While the estuary-wide loss of eelgrass did not result in fewer fish or less biomass, it led to changes in species composition. The post-eelgrass decline period was characterized by increases in flatfish (mainly Citharichthys stigmaeus) and staghorn sculpin (Leptocottus armatus), and decreases in habitat specialists including bay pipefish (Syngnathus leptorhynchus) and shiner perch (Cymatogaster aggregata). There were similar trends inside and outside of remnant eelgrass patches. These findings support evidence across multiple ecosystems suggesting that the predominance of habitat-specialists predicts whether or not habitat loss leads to an overall decline in fish abundance. In addition, loss of critical habitats across seascapes can restrict population connectivity and lead to range contraction. For bay pipefish, the loss of eelgrass in Morro Bay is likely to create a population biogeographic divide. Currently, Morro Bay is dominated by flatfish and sculpins, and the longevity of this new ecosystem state will depend on future eelgrass recovery dynamics supported by ecosystem-based management approaches

Erenumab in chronic migraine: Patient-reported outcomes in a randomized double-blind study.

OBJECTIVE: To determine the effect of erenumab, a human monoclonal antibody targeting the calcitonin gene-related peptide receptor, on health-related quality of life (HRQoL), headache impact, and disability in patients with chronic migraine (CM). METHODS: In this double-blind, placebo-controlled study, 667 adults with CM were randomized (3:2:2) to placebo or erenumab (70 or 140 mg monthly). Exploratory endpoints included migraine-specific HRQoL (Migraine-Specific Quality-of-Life Questionnaire [MSQ]), headache impact (Headache Impact Test-6 [HIT-6]), migraine-related disability (Migraine Disability Assessment [MIDAS] test), and pain interference (Patient-Reported Outcomes Measurement Information System [PROMIS] Pain Interference Scale short form 6b). RESULTS: Improvements were observed for all endpoints in both erenumab groups at month 3, with greater changes relative to placebo observed at month 1 for many outcomes. All 3 MSQ domains were improved from baseline with treatment differences for both doses exceeding minimally important differences established for MSQ-role function-restrictive (≥3.2) and MSQ-emotional functioning (≥7.5) and for MSQ-role function-preventive (≥4.5) for erenumab 140 mg. Changes from baseline in HIT-6 scores at month 3 were -5.6 for both doses vs -3.1 for placebo. MIDAS scores at month 3 improved by -19.4 days for 70 mg and -19.8 days for 140 mg vs -7.5 days for placebo. Individual-level minimally important difference was achieved by larger proportions of erenumab-treated participants than placebo for all MSQ domains and HIT-6. Lower proportions of erenumab-treated participants had MIDAS scores of severe (≥21) or very severe (≥41) or PROMIS scores ≥60 at month 3. CONCLUSIONS: Erenumab-treated patients with CM experienced clinically relevant improvements across a broad range of patient-reported outcomes. CLINICALTRIALSGOV IDENTIFIER: NCT02066415. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that for patients with CM, erenumab treatment improves HRQoL, headache impact, and disability