Corporate Philanthropy: A Systematic Review

A systematic review of the corporate philanthropy literature is conducted. A sample of 60 academic articles was created and analyzed. The sample was examined to (1) develop a definition of corporate philanthropy contrasting it with related concepts; (2) review how corporate philanthropy has been examined theoretically; (3) review how it has been operationalized and determine commonly examined control, independent and dependent variables; (4) the societal implications of corporate philanthropy and (5) identify gaps in the literature and areas for future research. Findings suggest there is little cohesion in the literature regarding a standard definition, wide use of theories to situate corporate philanthropy, and several narrow conceptualizations with opportunities for an empirical and theoretical investigation to enhance the understanding of corporate philanthropy. The gaps identified in the literature review consist of (1) the further study of corporate philanthropy as an independent variable to determine the impacts of corporate action; (2) whether there is a certain amount of optimality associated with corporate donations; (3) whether there are cultural limitations to the findings of attitude towards corporate philanthropy, and (4) a fuller study of the risks and/or benefits posed by corporate philanthropy to society

Regression Rate Study of PVC/HTPB Hybrid Rocket Fuels

In the present study an effort is made to investigate the local regression rate, average regression rate through the effect of oxidizer injection pressure. For experimental investigation a lab scale ballistic test motor is designed and number of static test firing are carried out at different gaseous oxidizer injection pressure. The injection pressure is varied from 150psi to 420psi and a Swirl Injector and a conventional Shower Head Injector are used for the oxidizer injection from oxidizer chamber to fuel grain port. The local regression rate is obtained from the unburnt fuel web thickness after 10.5 second of test firing. Further, the investigation of regression rate of PVC and HTPB solid fuels are depended on mass flux of oxidizer as the regression rate shown a decreasing trend from head end to nozzle end. From the present analysis, it can be summarized that for PVC solid fuel regression rate is completely dependent on swirl injection of oxidizer, as well as the oxidizer injection pressure

Control strategy for selective compensation of power quality problems through three-phase four-wire UPQC

This paper presents a novel control strategy for selective compensation of power quality (PQ) problems, depending upon the limited rating of voltage source inverters (VSIs), through a unified power quality conditioner (UPQC) in a three-phase four-wire distribution system. The UPQC is realized by the integration of series and shunt active power filters (APFs) sharing a common dc bus capacitor. The shunt APF is realized using a three-phase, four-leg voltage source inverter (VSI), while a three-leg VSI is employed for the series APF of the three-phase four-wire UPQC. The proposed control scheme for the shunt APF, decomposes the load current into harmonic components generated by consumer and distorted utility. In addition to this, the positive and negative sequence fundamental frequency active components, the reactive components and harmonic components of load currents are decomposed in synchronous reference frame (SRF). The control scheme of the shunt APF performs with priority based schemes, which respects the limited rating of the VSI. For voltage harmonic mitigation, a control scheme based on SRF theory is employed for the series APF of the UPQC. The performance of the proposed control scheme of the UPQC is validated through simulations using MATLAB software with its Simulink and Power System Block set toolboxes

A novel control strategy of three-phase, four-wire UPQC for power quality improvement

The current paper presents a novel control strategy of a three-phase, four-wire Unified Power Quality (UPQC) to improve power quality. The UPQC is realized by the integration of series and shunt active power filters (APF) sharing a common dc bus capacitor. The realization of shunt APF is carried out using a three-phase, four-leg Voltage Source Inverter (VSI), and the series APF is realized using a three-phase, three-leg VSI. To extract the fundamental source voltages as reference signals for series APF, a zero-crossing detector and sample-and-hold circuits are used. For the control of shunt APF, a simple scheme based on the real component of fundamental load current (I CosΦ) with reduced numbers of current sensors is applied. The performance of the applied control algorithm is evaluated in terms of power-factor correction, source neutral current mitigation, load balancing, and mitigation of voltage and current harmonics in a three-phase, four-wire distribution system for different combinations of linear and non-linear loads. The reference signals and sensed signals are used in a hysteresis controller to generate switching signals for shunt and series APFs. In this proposed UPQC control scheme, the current/voltage control is applied to the fundamental supply currents/voltages instead of fast-changing APF currents/voltages, thus reducing the computational delay and the required sensors. MATLAB/Simulink-based simulations that support the functionality of the UPQC are obtained

Testing of Paraffin-based Hybrid Rocket Fuel using Gaseous Oxygen Oxidiser

A series of paraffin-based hybrid rocket fuel has been studied experimentally in a laboratory-scale motor. To enhance the regression rate of paraffin solid fuel, three types of grain configurations: Cylindrical, star, and helical grain configurations of paraffin wax have been developed and tested with gaseous oxygen. The helical fuel grain presented best performance among all the test ports. About 40.2 per cent and 20.6 per cent regression rates are increased by burning paraffin fuel with helical and star grain configuration respectively, as compared to cylindrical grain configuration at Gox=0.0191 g/mm2s. The regression rates were significantly influenced by the oxygen injection pressure varied between 344.7 kPa and 620.5 kPa. Furthermore, the experimentally obtained exponents of oxidizer mass flux for all three grain configurations have been found to be significantly different from those of the classical hybrid system. Finally, thrust-time traces for all three grain configurations were also studied. The result shown no significant increase or decrease in the amplitude of the thrust oscillations.Defence Science Journal, 2012, 62(5), pp.277-283, DOI:http://dx.doi.org/10.14429/dsj.62.234

New control algorithms for three-phase four-wire unified power quality conditioner — a simulation study

n this paper, some new control algorithms are proposed for three-phase four-wire Unified Power Quality Conditioner. These control algorithms are based on the combination of Unit Vector Template Generation (UVTG) with Power Balance Theory (PBT), single phase d-q theory, Synchronous Current Detection (CSD) technique, and I CosΦ theory. The performance of each control algorithm of UPQC is evaluated in terms of power factor correction, load balancing and source neutral current mitigation, and voltage and current harmonic mitigation. The performance of proposed control algorithms are compared with synchronous reference frame (SRF) based control algorithm. In each proposed control scheme of the three-phase four-wire UPQC, the current/voltage control is applied over the fundamental supply currents/ load voltages instead of fast changing APFs currents/voltages, thereby reducing the effects of computational delay. Moreover, the load neutral or shuntAPF neutral currents are not sensed hence the required current sensors are reduced

A search for a consistent model for the electromagnetic spectrum of the crab nebula

An attempt is made to search for a consistent model to explain the electromagnetic spectrum of the Crab nebula (Tau A). It is assumed that there is a continuous injection of electrons at the centre of the nebula with an energy spectrum E-1.54 as evidenced by radio data. This spectrum must steepen to a slope larger than 2 at some energy Ei in order to ensure that the energy input into electrons remains finite. The spectrum must also steepen beyond an energy Ec depending on the magnetic field because of synchrotron energy losses. Two types of models are considered: Class I, in which the whole nebula is characterised by a uniform magnetic field, and Class II, in which besides the general field H0, small filamentary regions of strong field Hs are postulated. In models of Class I, the best fit to the observed data is obtained when E t >E c and H0⋍5×10-4 gauss. However, this predicts a decrease in X-ray source size beyond ~40 KeV. There are two possibilities of Class II model depending on the residence time of electrons in strong field regions being small or large. The former case explains the flattening in the optical spectrum

Prevalence of Gram-negative Pathogens and their antimicrobial susceptibility in bacterial meningitis in pediatric cases

The present study was conducted to find out the prevalence and spectrum of Gram negative pathogens causing bacterial meningitis and their antimicrobial susceptibility pattern in a tertiary care hospital. The cerebrospinal fluid (CSF) (3-5 ml) was collected from 638 admitted children clinically suspected of septic meningitis. Bacterial isolates were identified and antimicrobial susceptibility was assessed by the Kirby-Bauer disk diffusion method. Of the 638 samples tested 102 (15.99%) were culture positive. Male to female (M:F) ratio was 1.62:1. The maximum incidence of 45 (44.12%) cases was found in children (1-12 yrs); in institutional deliveries the incidence was 58 (56.86%) cases. Further, the incidence of 51 cases was found from May to August. Escherichia coli (E. coli) were commonest, seen in 9 (25%) cases followed by Acinetobacter spp., Citrobacter spp. and Klebsiella spp. with 6 (16.67%) cases each. Enterobacter spp., Neisseria spp. and Pseudomonas aeruginosa were isolated in 3 (8.33%) cases each. E. coli, Acinetobacter spp, Citrobacter spp and Klebsiella spp isolates were 100% susceptible to meropenem, piperacillin-tazobactam and cefoperazone-sulbactam and 100% resistant to cotrimoxazole and tetracycline. All strains of Neisseria spp, Enterobacter spp and Pseudomonas spp. were 100% susceptible to meropenem followed by gatifloxacin. These were 100% resistant to tetracycline and cotrimoxazole. Neisseria spp. were also 100% susceptible to pristinamycin. In septic meningitis Gram negative organisms are less common (35.29%). Of the isolates, more common Gram negative isolates included E. coli, Acinetobacter Spp., Citrobacter Spp., and Klebsiella spp. and these isolates were 100% susceptible to meropenem, piperacillin-tazobacatam and cefoperazone-sulbactam. Hence, empirical therapy should be formulated according to antimicrobial susceptibility patterns

Cross-referencing and Thesaurus maintenance

The development of thesauri in science and technology is briefly discussed. The important aspects of the structure and format of a thesaurus are mentioned. The need for revising a thesaurus, the structural changes that may occur in course of time, and the problems of maintaining a thesaurus are indicated. It is the need that should determine the frequency of revision, rather than any other exigency. The types of relations implied in the cross-reference structures in thesauri are briefly discus- sed. The cross-reference structures in TEST, Thesaurofacet, INIS The Stresses the point that the policy regarding saurus etc, are examined. the cross-referencing in thesauri should be stated explicitly, if proper and useful studies are to be undertaken regarding the cross-reference structures, and points out that such a policy statement is of help in the maintenance of thesauri and usable form. The two types of approaches suggested Kochen and others for the study of properties of cross-reference of structures are mentioned