The Impact of the Parabolic Dish Concentrator on the Wind Induced Heat Loss From Its Receiver

Abstract To achieve higher operating temperatures, power output and system efficiencies in parabolic dish cavity receivers, larger dish sizes and structures are used to increase the concentration ratio. This increases capital investment and installation costs, which in turn places a much stronger emphasis on accurately predicting the performance of the system and the heat loss from it. Numerous studies have investigated the natural convection heat losses from cavity receivers, and some have examined a cavity exposed to wind. However, the effect of the dish on the wind flow and subsequently the heat loss from the receiver has not been widely considered. In this work, computational fluid dynamics was used to model the flow of air around a parabolic dish concentrator operating at varying angles of operation. The flow fields were validated using wind tunnel testing and published data regarding the aerodynamic characteristics of parabolic dishes. The results showed that the orientation of the dish has a significant effect on the flow structure near the receiver. Subsequently, using the validated method, the convective heat loss from the receiver of a large parabolic dish system was determined for a range of operating conditions. The results support the assertion that the flow characteristics near the cavity receiver aperture depend strongly on the orientation of the dish structure. This resulted in the calculated heat loss being up to 40% lower than previous studies where the presence of the dish was included. As such, the wind flow around the dish needs to be accounted for when analyzing the performance of parabolic dish systems to avoid an overly conservative and hence more expensive design

Identifying line-to-ground faulted phase in low and medium voltage AC microgrid using principal component analysis and supervised machine-learning

© 2018 IEEE. A supervised machine-learning based approach for faulted phase identification in bolted, low- A nd high-impedance line-to-ground faults using principal component analysis for feature extraction from multiple input signals is presented in this paper. DIgSILENT PowerFactory is used for simulating the underlying microgrid to obtain fault related data, while MATLAB is used for machine learning application. A 15-fold cross validation is applied to the training dataset for evaluation of different machine learning models and the results show supreme performance compared to previous methods

Multi-Order Statistical Descriptors for Real-Time Face Recognition and Object Classification

We propose novel multi-order statistical descriptors which can be used for high speed object classification or face recognition from videos or image sets. We represent each gallery set with a global second-order statistic which captures correlated global variations in all feature directions as well as the common set structure. A lightweight descriptor is then constructed by efficiently compacting the second-order statistic using Cholesky decomposition. We then enrich the descriptor with the first-order statistic of the gallery set to further enhance the representation power. By projecting the descriptor into a low-dimensional discriminant subspace, we obtain further dimensionality reduction, while the discrimination power of the proposed representation is still preserved. Therefore, our method represents a complex image set by a single descriptor having significantly reduced dimensionality. We apply the proposed algorithm on image set and video-based face and periocular biometric identification, object category recognition, and hand gesture recognition. Experiments on six benchmark data sets validate that the proposed method achieves significantly better classification accuracy with lower computational complexity than the existing techniques. The proposed compact representations can be used for real-time object classification and face recognition in videos. 2013 IEEE.This work was supported by NPRP through the Qatar National Research Fund (a member of Qatar Foundation) under Grant 7-1711-1-312.Scopu

MAST Propellant and Delivery System Design Methods

A Mars Aerospace Taxi (MAST) concept and propellant storage and delivery case study is undergoing investigation by NASA's Element Design and Architectural Impact (EDAI) design and analysis forum. The MAST lander concept envisions landing with its ascent propellant storage tanks empty and supplying these reusable Mars landers with propellant that is generated and transferred while on the Mars surface. The report provides an overview of the data derived from modeling between different methods of propellant line routing (or "lining") and differentiate the resulting design and operations complexity of fluid and gaseous paths based on a given set of fluid sources and destinations. The EDAI team desires a rough-order-magnitude algorithm for estimating the lining characteristics (i.e., the plumbing mass and complexity) associated different numbers of vehicle propellant sources and destinations. This paper explored the feasibility of preparing a mathematically sound algorithm for this purpose, and offers a method for the EDAI team to implement

Phytochemical and Ethno-Pharmacological Review of the Genus Araucaria – Review

Distribution, traditional uses, isolated chemical constituents and pharmacological activities of some common species of the genus Araucaria are reviewed in this paper. Almost 19 species belong to the genus, Araucaria. It is indigenous to North America. Biflavanoid, diterpene, phenyl propanoid and lignans are abundant in the genus. The most common pharmacological activity of Araucaria in modern medicines is anti-inflammatory. It also possesses other pharmacological activities such as antiulcer, antiviral, neuro-protective, anti-depressant and anti-coagulant. The aim of the present paper is to present an extensive review of the plants in this genus including their traditional uses, chemical constituents and pharmacology.Keywords: Araucaria, Ethnopharmacology, Phytochemistry, Biflavanoids, Diterpen

A Pilot Study to Evaluate the Effects of Cerebroprotein Hydrolysate on Neurological Outcomes and Hospital Stay in Patients Admitted for Ischemic and Hemorrhagic Stroke

Introduction: Neurological stroke is the most common cause of disability and leaves nearly 65% of survivors with sensory, motor and coordinative disabilities. At present, there are no therapies to prevent long-term neurological deficits after stroke. Many neuroprotective drugs are being tested with the aim to ensure these effects. Preclinical studies have shown a modulatory effect of cerebroprotein hydrolysate on synaptic remodeling and facilitated synaptic transmission. Material and methods: This was a hospital-based, open-label pilot study conducted in a tertiary care hospital of North India. All patients admitted with a diagnosis of stroke both ischemic and hemorrhagic, were included in the study. Patients were randomized into two groups. The test group was given cerebroprotein hydrolysate, along with standard treatment for stroke, whereas the other group was kept on standard treatment for stroke as per the latest guidelines, without cerebroprotein. Results: A total of 50 patients of stroke, admitted in a tertiary care center were included in the study. The mean age of the patients was 65.7 ± 11.86 years. Twenty-six (52%) were males and 24 (48%) were females. Out of the total 50 patients, 23 (46%) had ischemic stroke and 27 (54%) had hemorrhagic stroke. Twenty (40%) had diabetes, 37 (74%) had hypertension, 8 (16%) were known cases of coronary artery disease, 28 (56%) had dyslipidemia, 22 (44%) were smokers, 7 (14%) had a history of ethanol consumption and 13 (26%) were obese. Mean Barthel score at admission was 21.2 ± 11.3 and mean Rankin score at admission was 3.6 ± 1.37. Mean Barthel score at end of treatment was 53.9 ± 28.72 and mean Rankin score at end of treatment was 2.6 ± 1.65. The mean duration of admission was 6.8 ± 3.57 days. Conclusion: The current study highlights the role of cerebroprotein hydrolysate in improving the neurological scores and reducing hospital stay among patients hospitalized with stroke

Median survival time of patients after transcatheter chemo-embolization for hepatocellular carcinoma

Objective: To determine the effect on survival after transarterial chemoembolization (TACE) in patients with unresectable hepatocellular carcinoma (HCC).Design: Longitudinal cohort study.PLACE AND DURATION OF STUDY: Radiology Department, The Aga Khan University Hospital, Stadium Road, Karachi, from December 1997 to September 2005.PATIENTS AND Methods: Patients undergoing TACE procedure for HCC were prospectively followed. Fortythree patients were enrolled from December 1997 to March 2003 in the study and subjected to chemoembolization therapy. Eight out of 43 patients were excluded from the study, who lost to follow-up. All the patients were followed till their death. Median and mean survival were calculated.Results: The median survival of these 35 patients was 410 days (13.6 months), with 95% confidence interval (236 days lower bound and 536 days upper bound). Mean survival time was 603 days (20.1 months) with 95% confidence interval (394 days lower bound and 812 days upper bound). There was significant difference in mean survival time (in days) by Child s Pugh class (chi(2) = 12.384; df=2, p-value=0.002).CONCLUSION: The study showed that TACE is an effective palliative treatment. TACE increases the median survival time

Analysis of final state lepton polarization-dependent observables in H→ℓ+ℓ−γH\to \ell^{+}\ell^{-} \gamma in the SM at loop level

Recently, the CMS and ATLAS collaborations have announced the results for $H\rightarrow Z[\rightarrow \ell^{+}\ell^{-}]\gamma$ with $\ell=e$ or $\mu$, where $H\rightarrow Z\gamma$ is a sub-process of $H\rightarrow \ell^{+} \ell^{-} \gamma$. This semi-leptonic Higgs decay receives loop induced resonant $H\rightarrow Z[\rightarrow \ell^{+}\ell^{-}]\gamma$ as well as non-resonant contributions as discussed in. To probe further features coming from these contributions to $H\rightarrow \ell^{+} \ell^{-} \gamma$, we suggest that the polarization of the final state lepton is an important parameter. We show that the resonant and non-resonant cross-terms play an important role when the polarization of final state lepton is taken into account, which is negligible in the case of un-polarized leptons. For this purpose, we have calculated the polarized decay rates and the longitudinal, normal and transverse polarization asymmetries. We find that these asymmetries purely come from the loop contributions and are helpful to further investigate the resonant and non-resonant nature of $H\rightarrow Z[\rightarrow \ell^{+}\ell^{-}]\gamma$ decay. We observe that for $\ell=e,\mu$, the longitudinal decay rate is highly suppressed around $m_{\ell\ell}\approx 60$GeV when the final lepton spin is $-\frac{1}{2}$, dramatically increasing the corresponding lepton polarization asymmetries. Furthermore, we analyze another clean observable, the ratio of decay rates $\Gamma$, $R^{\ell\ell'}\equiv \frac{\Gamma_{H\rightarrow \ell^{+} \ell^{-} \gamma}}{\Gamma_{H\rightarrow \ell^{'+} \ell^{'-} \gamma}}$, where $\ell$ and $\ell'$ refer to different final state lepton generations. Therefore, the precise measurements of these observables at CMS and ATLAS can provide a fertile ground to test not only the Standard Model (SM) but also to examine the signatures of possible new physics (NP) beyond the SM.Comment: 28 pages, 7 figure

Evaluation of erectile dysfunction with color Doppler sonography

Objective: To assess the role of Color Doppler Sonography in the evaluation of erectile dysfunction.Methods: A cross-sectional study was conducted at the Radiology Department, Aga Khan University Hospital Karachi from 5-6-2002 to 2-9-2003. All consecutive patients presenting with erectile dysfunction and undergoing penile color Doppler evaluation with injection PGE1 20 mcg were included in this study.Results: A total of 70 patients with an age range of 24-70 years (mean 41 +/- 12.25 years) were included in the study. A normal response was noted in 45 (psychogenic) cases. Vasculogenic causes were observed in 23 patients, 12 with arterial insufficiency and 11 with venous leak. Peyronie\u27s disease was diagnosed in 2 patients.CONCLUSION: Color Doppler evaluation of erectile dysfunction is an effective method for differentiating psychogenic and vasculogenic causes of erectile dysfunction