Transient Response Of A Packed Bed For Both Sensible And Latent Thermal Energy Storage

The present work was undertaken to provide a model which accurately predicts the performance of a packed bed energy storage system utilizing spherically encapsulated phase-change material (PCM). Two models were developed which are referred to as the first-order and second-order models. Both models involve modeling of the phase-change material as a conduction problem with both sensible and latent energy storage and include consideration of the temperature gradients in both phases. Both models include the solution of the energy equation for the fluid passing through the packed bed. In the second-order model, both the intra-particle conduction and the dispersion effects in the energy transporting fluid are considered, whereas in the first-order model only the intra-particle conduction effects are considered. Numerical results obtained with both models have been compared with experimental results available in the published literature and with experimental data previously obtained at University of Tennessee. Of major importance to any computation is the treatment of the convective heat transfer coefficient between the fluid and the packed bed particles. It was determined that existing correlation equation for the heat transfer coefficient are quite suitable. Also, confirmation of the convective heat transfer coefficient between the capsules and the fluid can be accurately determined by matching the exiting fluid temperature variation with time at the exit obtained with the second-order model with that obtained by experiment. A specific feature of both models is the use of a physically correct treatment of the exiting fluid temperature boundary condition. Both analytical models accommodate ·subcooling and superheating for PCM melting and freezing situations, respectively, as well as supercooling of the PCM in the computer simulation. The significance of subcooling or superheating depends upon the magnitude of the subcooling or superheating. For example, when using NA HPO . 12H O as the PCM, and a ratio of the length to the diameter of the bed larger than 1. 0. the neglecting of subcooling would result in an error in the total energy stored of about 1/2 percent for each degree of subcooling. Previously reported analyses in the literature do not include the effect of subcooling or superheating. Both the first-order and second-order models of the present study can be used to predict the melting/freezing time, the melting/freezing front location in the packed bed, and the temperature history of both the transporting fluid and the PCM in the bed. For the case of small Peclet numbers, comparison with experiment indicates that the first-order model results in significantly greater error than does the second-order model; it does, however, provide an adequate approximation for the latent heat storage in the bed. For Peclet number greater than 200, the difference between the results from the two models is typically less than 10%. The use of the first-order model requires only about one-fourth as much computer time as does the second-order model. The second-order model is shown to provide very accurate results when compared with experimental data in the published literature

Arbitrary Shape Electromagnetic Transparent Device Based on Laplace’s Equation

Transparent device is deliberately-designed electromagnetic structure that is transparent to electromagnetic wave. It can be used as a radome structure which is capable of protection antenna inside without sacrificing its performance. In this paper, two-dimensional (2D) arbitrary shape electromagnetic transparent device is designed based on transformation optics. Laplace’s equation is adopted to construct the coordinate mapping between the original space and the transformed space. The design method is flexibly extended to three-dimensional (3D) case, which greatly enhances the applicability of transparent device. The protection of a horn antenna is taken as an example to show the effectiveness of the transparent device. Since the performance of the transparent device is independent on the inner antenna, it can be designed separately. Full-wave simulations are made to validate the results

DIGAP - a Database of Improved Gene Annotation for Phytopathogens

<p>Abstract</p> <p>Background</p> <p>Bacterial plant pathogens are very harmful to their host plants, which can cause devastating agricultural losses in the world. With the development of microbial genome sequencing, many strains of phytopathogens have been sequenced. However, some misannotations exist in these phytopathogen genomes. Our objective is to improve these annotations and store them in a central database DIGAP.</p> <p>Description</p> <p>DIGAP includes the following improved information on phytopathogen genomes. (i) All the 'hypothetical proteins' were checked, and non-coding ORFs recognized by the Z curve method were removed. (ii) The translation initiation sites (TISs) of 20% ~ 25% of all the protein-coding genes have been corrected based on the NCBI RefSeq, ProTISA database and an <it>ab initio </it>program, GS-Finder. (iii) Potential functions of about 10% 'hypothetical proteins' have been predicted using sequence alignment tools. (iv) Two theoretical gene expression indices, the codon adaptation index (CAI) and the <it>E</it>(<it>g</it>) index, were calculated to predict the gene expression levels. (v) Potential agricultural bactericide targets and their homology-modeled 3D structures are provided in the database, which is of significance for agricultural antibiotic discovery.</p> <p>Conclusion</p> <p>The results in DIGAP provide useful information for understanding the pathogenetic mechanisms of phytopathogens and for finding agricultural bactericides. DIGAP is freely available at <url>http://ibi.hzau.edu.cn/digap/</url>.</p

SDSS J163459.82+204936.0: A Ringed Infrared-Luminous Quasar with Outflows in both Absorption and Emission Lines

SDSS J1634+2049 is a local (z = 0.1293) infrared-luminous quasar with LIR= 10^11.91 Lsun. We present a detailed multiwavelength study of both the host galaxy and the nucleus. The host galaxy demonstrates violent, obscured star formation activities with SFR ~ 140 Msun yr^-1, estimated from either the PAH emission or IR luminosity. The optical to NIR spectra exhibit a blueshifted narrow cuspy component in Hb, HeI5876,10830 and other emission lines consistently with an offset velocity of ~900 km/s, as well as additional blueshifting phenomena in high-ionization lines , while there exist blueshifted broad absorption lines (BALs) in NaID and HeI*3889,10830, indicative of the AGN outflows producing BALs and emission lines. Constrained mutually by the several BALs with CLOUDY, the physical properties of the absorption-line outflow are derived as follows: 10^4 < n_H <= 10^5 cm^-3, 10^-1.3 <= U <= 10^-0.7 and 10^22.5<= N_H <= 10^22.9 cm^-2 , similar to those derived for the emission-line outflows. The similarity suggests a common origin. Taking advantages of both the absorption lines and outflowing emission lines, we find that the outflow gas is located at a distance of 48 - 65 pc from the nucleus, and that the kinetic luminosity of the outflow is 10^44-10^46 erg s^-1. J1634+2049 has a off-centered galactic ring on the scale of ~ 30 kpc that is proved to be formed by a recent head-on collision by a nearby galaxy. Thus this quasar is a valuable object in the transitional phase emerging out of dust enshrouding as depicted by the co-evolution scenario.Comment: 13 figures, 6 tables; accepted for publication in Ap

A Novel Animal Model for Subarachnoid Hemorrhage in Rabbits - Pathology due to Hemorrhage

The Pathophysiological course of subarachnoid hemorrhage (SAH) is not completely understood, such as  how and why blood or its lysate can influence the brain. Although many SAH animal models have previously  been reported, none are suitable for research in this field. The aim of the present study was to establish  such an animal model. Twenty New Zealand rabbits were divided into two groups, a control group and  a SAH group (n=10). Blood was lysed using an in vitro freeze-thaw method. After anesthesia, 0.9 ml of  cerebrospinal fluid was drawn from both groups. An identical volume of heparinized hemolysate was then  slowly injected into the cisterna magna of the SAH group animals. Control group animals while the control  group received heparinized isotonic sodium chloride solution. Forty-eight hours post-injection, samples  were excised after perfusion fixation for further determinations. The degree of cerebral vasospasm was  evaluated by measuring the cross-sectional area of the basilar arterial lumen, and brain damage was examined  by TUNEL staining. Weight, blood pressure and saturation of blood oxygen showed no statistical differences  between groups. The cross-sectional area of the arterial lumen in the SAH group was roundly  0.402 mm2, which was statistically the same as that for the control group (0.435 mm2). The apoptosis index  for the SAH group was significantly higher than that for the control group. Taken together, our results show  that this model is effective in reproducing the influence of blood on the brain after SAH and, at the same  time, strictly excludes influences on the brain by other factors. Thus, this model can effectively be applied  to investigate blood-related neuropathophysiology following SAH.

Colorectal cancer screening with fecal occult blood test: A 22-year cohort study.

The aim of the present study was to investigate the efficacy of colorectal cancer (CRC) screening with a three-tier fecal occult blood test (FOBT) in the Chinese population. The study was performed between 1987 and 2008 at the Beijing Military General Hospital, in a cohort of army service males and females aged &gt;50 years. Between 1987 and 2005, a three-tier screening program, comprising guaiac-based FOBTs (gFOBTs), followed by immunochemical FOBTs for positive guaiac test samples and then colonoscopy for positive immunochemical test subjects, was performed annually. The cohort was followed up until 2008. The cohort included 5,104 subjects, of which, 3,863 subjects participated in screening (screening group) and 1,241 did not (non-screening group). The two groups did not differ in age, gender or other major risk factors for colon cancer. Overall, 36 CRCs occurred in the screening group and 21 in the non-screening group. Compared with the non-screening group, the relative risk for the incidence and mortality of CRC was 0.51 [95% confidence interval (CI), 0.30-0.87] and 0.36 (95% CI, 0.18-0.71), respectively, in the screening group. The general sensitivity of this three-tier FOBT was 80.6% (95% CI, 65.3-91.1). Thus, annual screening using the three-tier FOBT program may reduce the CRC incidence and mortality rate

Characteristic analysis of α-fetoprotein-producing gastric carcinoma in China

α-Fetoprotein-producing gastric cancer (AFPGC) is a rare type of gastric cancer. The largest population of patients with AFPGC is found in China. In the present study, a total of 4,779 GC patients, including 317 AFPGC patients, from 11 clinical studies in China with a general AFPGC/GC ratio of 6.63% were summarized and analyzed. On the basis of analysis of the clinical data, the patients with AFPGC had larger tumor size, weaker cell differentiation, worse histopathological types, deeper serosal infiltration, more lymph node and liver metastases, poorer stages, shorter survival time and more positive expression of vascular endothelial growth factors than the patients without AFPGC. Our observation is consistent with previous results reported in studies of AFPGC. Overall, AFPGC is a subtype of GC with a poor prognosis