KIVA is a widely used (;ode for combustion simulation in engines. We discuss its shortcomings in approximating real gas turbine combustors and what might be done to improve its performance. It is assumed that the combustion and CFD phenomena are modeled with complete accuracy and that the solution of discretized versions of these models is also accurate. Thus the focus is on the geometry, grid ...

The purpose of present paper is simulation a direct injection stratified charge natural gas engine. The KIVA-3V code was used for gaseous fuel injection simulation. Compression and expansion stroke of engine cycle is simulated using KIVA-3V code. In cylinder fuel equivalence ratio distribution criterion is used for studying mesh independency. The results show that 550000 cells number is suff...

Comparisons between numerical results and experimental data for a homogeneous charge compression ignition (HCCI) engine with optical accessibility are being presented in this paper. The KIVA – 3V program, a general purpose combustion routine, is being enhanced by implementing the optimized Shell model for the ignition process, applying the extended Zeldovich formulation for nitrogen oxide forma...

A new phenomenological model, the TP (Temperature Phase) model, is presented to carry out optimization calculations for turbulent diffusion combustion in a high-pressure common rail diesel engine. Temperature is the most important parameter in the TP model, which includes two parts: an auto-ignition and a soot model. In the auto-ignition phase, different reaction mechanisms are built for differ...

BACKGROUND Vertebral metastases are associated with significant pain, disability, and morbidity. Open surgery for fracture stabilization is often inappropriate in this cancer population due to a poor risk-benefit profile, particularly if life expectancy is short. Vertebroplasty and kyphoplasty are appealing adjunctive procedures in patients with malignancy for alleviation of intractable pain. H...

BACKGROUND Bullying refers to verbal, physical or psychological aggression repeated over time that is intended to cause harm or distress to the victims who are unable to defend themselves. It is a key public health priority owing to its widespread prevalence in schools and harmful short- and long-term effects on victims' well-being. There is a need to strengthen the evidence base by testing inn...

This paper reports the results of a large-scale field experiment designed to test the hypothesis that group membership can increase participation and prosocial lending for an online crowdlending community, Kiva. The experiment uses variations on a simple email manipulation to encourage Kiva members to join a lending team, testing which types of team recommendation emails are most likely to get ...

This study demonstrates the effectiveness of the KiVa antibullying program using a large sample of 8,237 youth from Grades 4-6 (10-12 years). Altogether, 78 schools were randomly assigned to intervention (39 schools, 4,207 students) and control conditions (39 schools, 4,030 students). Multilevel regression analyses revealed that after 9 months of implementation, the intervention had consistent ...

Kiva is an online philanthropic crowdsourcing platform that connects lenders with the borrowers in the third world. It is via the stories conveyed by the loan descriptions that the lenders get to know the borrowers and make the decision to help. In this project we study how the loan descriptions affect the funding speed of the loans. We train recurrent neural networks and long short-term memory...

Multi-agent path-finding (MAPF) is important for applications such as the kind of warehousing done by Kiva systems. Solving the problem optimally is NP-hard, yet finding lowcost solutions is important. Bounded-suboptimal MAPF algorithms, such as enhanced conflict-based search (ECBS), often do not perform well in warehousing domains with many agents. We therefore develop bounded-suboptimal MAPF ...