Fluidized-bed reactor modeling for production of silicon by silane pyrolysis

An ideal backmixed reactor model (CSTR) and a fluidized bed bubbling reactor model (FBBR) were developed for silane pyrolysis. Silane decomposition is assumed to occur via two pathways: homogeneous decomposition and heterogeneous chemical vapor deposition (CVD). Both models account for homogeneous and heterogeneous silane decomposition, homogeneous nucleation, coagulation and growth by diffusion of fines, scavenging of fines by large particles, elutriation of fines and CVD growth of large seed particles. At present the models do not account for attrition. The preliminary comparison of the model predictions with experimental results shows reasonable agreement. The CSTR model with no adjustable parameter yields a lower bound on fines formed and upper estimate on production rates. The FBBR model overpredicts the formation of fines but could be matched to experimental data by adjusting the unkown jet emulsion exchange efficients. The models clearly indicate that in order to suppress the formation of fines (smoke) good gas-solid contacting in the grid region must be achieved and the formation of the bubbles suppressed

Standards relevant to transformers – Part IX

This part of the column covers a list of standards on the range of accessories used with power transformers and reactors. These standards apply to a wide range of accessories and fittings mounted on power transformers and reactors. They outline the service conditions and mechanical requirements common to all the accessories, as well as operational requirements specific to each device

Standards relevant to transformers - Part IX

The eleventh part of the column includes a list of international standards and CIGRE technical brochures covering the installation, operation and maintenance of power transformers, essential for ensuring their proper operation

Orienting Graphs to Optimize Reachability

The paper focuses on two problems: (i) how to orient the edges of an undirected graph in order to maximize the number of ordered vertex pairs (x,y) such that there is a directed path from x to y, and (ii) how to orient the edges so as to minimize the number of such pairs. The paper describes a quadratic-time algorithm for the first problem, and a proof that the second problem is NP-hard to approximate within some constant 1+epsilon > 1. The latter proof also shows that the second problem is equivalent to ``comparability graph completion''; neither problem was previously known to be NP-hard

Health Seeking Behavior among Rickshaw Pullers in Delhi and Their Acceptance of Using Mobile Phoneto Seek Health Information

Background: Rickshaw pullers of India are one among the vulnerable population in India and have no or limited access to health service and have poor health condition. Most of them are migrants and have shifted to urban cities like Delhi and Agra to earn a livelihood to support their families left behind. Low socioeconomic status, unhygienic living environment, and improper diet, lead to their health problems. As they are unable to visit their families frequently they keep in touch with them through mobile phones. Although health information seeking of the consumers through the mobile has received great attention, limited attempt has been made to understand the same in context of vulnerable population. The aim of this study is to explore the health seeking behavior of rickshaw pullers in Delhi and their acceptance towards the use of mobile phones to seek health related information Subjects and Method: This was a qualitative study with case studies approach conducted at two metro stations and market place where there were significant available numbers of rickshaw pullers. A sample of 75 rickshaw pullers was selected by simple random sampling. The data were collected by survey of rickshaw pullers based on semi-structured questionnaires. Results: This study found out that more than 90% of the rickshaw pullers were migrants from North Indian states and 70% had migrated more than five years ago. Regarding their health seeking behavior most of them used home based cures or consulted pharmacies and local doctors. Many were unaware of the government health facilities and the services available to them. Their intention to seek health information through mobiles and use the information was influenced by the information quality, perceived value, ease of use, method and cost of receiving information and trust on the source. Conclusion: The current study throws light on the factors affecting the mobile based health information seeking behavior of the rickshaw pullers and provides valuable insights that can be used for developing mobile health interventions for the vulnerable population. Keywords: health information, mobile phones, rickshaw pullers, health seeking behavio

A survey on fiber nonlinearity compensation for 400 Gbps and beyond optical communication systems

Optical communication systems represent the backbone of modern communication networks. Since their deployment, different fiber technologies have been used to deal with optical fiber impairments such as dispersion-shifted fibers and dispersion-compensation fibers. In recent years, thanks to the introduction of coherent detection based systems, fiber impairments can be mitigated using digital signal processing (DSP) algorithms. Coherent systems are used in the current 100 Gbps wavelength-division multiplexing (WDM) standard technology. They allow the increase of spectral efficiency by using multi-level modulation formats, and are combined with DSP techniques to combat the linear fiber distortions. In addition to linear impairments, the next generation 400 Gbps/1 Tbps WDM systems are also more affected by the fiber nonlinearity due to the Kerr effect. At high input power, the fiber nonlinear effects become more important and their compensation is required to improve the transmission performance. Several approaches have been proposed to deal with the fiber nonlinearity. In this paper, after a brief description of the Kerr-induced nonlinear effects, a survey on the fiber nonlinearity compensation (NLC) techniques is provided. We focus on the well-known NLC techniques and discuss their performance, as well as their implementation and complexity. An extension of the inter-subcarrier nonlinear interference canceler approach is also proposed. A performance evaluation of the well-known NLC techniques and the proposed approach is provided in the context of Nyquist and super-Nyquist superchannel systems.Comment: Accepted in the IEEE Communications Surveys and Tutorial

​മത്സ്യോല്പാദനം മത്സ്യക്കുഞ്ഞുങ്ങളുടെ സംരക്ഷണത്തിലൂടെ

Conservation of Juvenile fishe

Enhancing mode stability of higher order modes in a multimode fiber

An innovative strategy to increase the modal stability of the higher order modes of multimode fiber is proposed where the modal stability is increased by more than 80% between LP05 and its neighboring antisymmetric modes

Short course chemotherapy for pulmonary tuberculosis in children

A total of 137 children with pulmonary tuberculosis were treated with one of the following 2 regimens: the first regimen consisted of two drugs namely isoniazid and rifampicin administered daily for nine months (9HR) and the second of isoniazid, rifampicin and pyrazinamide thrice a week for the first two months followed by isoniazid and rifampicin twice a week for the next 4 months (2 H 3 R 3 Z 3 /4H 2 R 2 ). The diagnosis was based on radiological abnormality which was classified as most probable (category A) and probable (category B). On admission, 56% of the patients were aged less than 5 years, tuberculin test with 1 TU was positive in 72% and a history of contact with a known case of tuberculosis present in 78%. Of the 137 patients, 50% were treated with regimen I and the remaining 50% were treated with regimen II while 41 % of the patients were classified as category A and 59% as category B. Culture was positive for M. tuberculosis in a total of 44 (32%) patients. The results were similar in both the regimens indicating that 6 months' intermittent therapy with 3 drugs in the initial 2 months' is as effective as the 9 months' daily therapy with 2 drugs. Both the nodal and parenchymal lesions resolved to the same extent at the end of treatment. The residual lesions continued to improve even after stopping treatment. Mortality and drop out rates were very low and adverse reactions negligible