Numerical study of combustion processes in afterburners

Mathematical models and numerical methods are presented for computer modeling of aeroengine afterburners. A computer code GEMCHIP is described briefly. The algorithms SIMPLER, for gas flow predictions, and DROPLET, for droplet flow calculations, are incorporated in this code. The block correction technique is adopted to facilitate convergence. The method of handling irregular shapes of combustors and flameholders is described. The predicted results for a low-bypass-ratio turbofan afterburner in the cases of gaseous combustion and multiphase spray combustion are provided and analyzed, and engineering guides for afterburner optimization are presented

Assessing The Correlation Between Per- And Polyfluoroalkyl Substances (pfas) Exposure And Cancer Incidence In The U.s.

AbstractThe study seeks to understand the relationship between key PFAS contaminants and their potential to cause cancer in the United States. It also aims to find out how different PFAS exposures affect different types of cancer and how food can increase or decrease the risk of getting cancer. The study used secondary data from the government and other reliable sources. The process looked at PFAS exposure, food malnutrition, and cancer rates in the population by using both descriptive and inferential statistics. After looking at socio-economic factors and their health effects on the public, the results showed that PFOS, PFHxS, and PFOA are the most common types of environmental pollutants. In urban areas, these contaminants are negatively linked to undernutrition. There was no significant link between PFAS exposure and thyroid, prostate, or non-Hodgkin\u27s lymphoma, but there were weak links found in breast, ovary, and bladder cancer. This link suggests that PFAS has a complex effect on the incidence of cancer. The study also showed that diet, especially not eating enough fruit, plays a big role in the risk of getting cancer. In conclusion, the study says that a multifaceted plan to prevent cancer that includes improving diet and lowering environmental pollution should be used. This is because the links between eating habits, environmental pollution, and cancer development are complicated

Stakeholder orientation and organizational performance in an emerging market

There has been research that studies Chinese firms’ stakeholder orientation but fails to identify Chinese firms’ specific stakeholder groups. In addition, little research in this line has been conducted so far to reflect recent Chinese constitutional transition. This study seeks to fill these gaps. It extends previous studies assuming that a fixed set of stakeholders is suitable for firms in different countries context, and identifies Chinese firms’ key stakeholder groups by adopting the descriptive approach of stakeholder theory. Based on this identification, the authors further examine how these stakeholder orientations influence organizational performance and how they interact. Interviews with managers from 107 firms show that customer, employee, shareholder, supplier, and competitors are perceived as Chinese firms’ most important stakeholders; empirical studies using data collected from 307 Chinese firms reveal that orientations towards these stakeholders enhance organizational performance. Moreover, there are synergy effects existing among customer orientation, supplier orientation, and competitor orientation, and between customer orientation and competitor orientation, while shareholder orientation has significant hindering effects upon competitor orientation as a reflection of recent institutional changes taking place in China

Calculation of Lightning Transient Responses on Wind Turbine Towers

An efficient method is proposed in this paper for calculating lightning transient responses on wind turbine towers. In the proposed method, the actual tower body is simplified as a multiconductor grid in the shape of cylinder. A set of formulas are given for evaluating the circuit parameters of the branches in the multiconductor grid. On the basis of the circuit parameters, the multiconductor grid is further converted into an equivalent circuit. The circuit equation is built in frequency-domain to take into account the effect of the frequency-dependent characteristic of the resistances and inductances on lightning transients. The lightning transient responses can be obtained by using the discrete Fourier transform with exponential sampling to take the inverse transform of the frequency-domain solution of the circuit equation. A numerical example has been given for examining the applicability of the proposed method

Contracting for IT Outsourcing with Asymmetric Information

IT outsourcing allows a business to reduce the cost of IT service delivery and improve the quality of IT service by taking advantage of the service provider’s economics of scale and technical expertise. However, the successful outsourcing of IT service is hampered by lack of guidance on how to design incentive contracts to encourage performance of the service provider, especially in the presence of information asymmetry and incentive divergence. In this article, we identify and characterize two asymmetric information factors: asymmetric effort information and asymmetric capability information. Depending on whether the service provider’s effort information and capability information is symmetric or not, we consider three information scenarios and characterize optimal incentive contracts for each scenario. We also introduce the concept of information value to quantify the adverse effects of the two asymmetric information factors. The results provide theoretical support for designing incentive contracts that mitigate the adverse effects of asymmetric information, and recommend effective guidance for activities so as to reduce the degree of information asymmetry