Analysis of controlled auto-ignition /HCCI combustion in a direct injection gasoline engine with single and split fuel injections

A multi-cycle three-dimensional CFD engine simulation programme has been developed and applied to analyze the Controlled autoignition (CAI) combustion, also known as homogeneous charge compression ignition (HCCI), in a direct injection gasoline engine. CAI operation was achieved through the negative valve overlap method by means of a set of low lift camshafts. In the first part of the paper, the effect of single injection timing on combustion phasing and underlying physical and chemical processes involved was examined through a series of analytical studies using the multi-cycle 3D engine simulation programme. The analyses showed that early injection into the trapped burned gases of a lean-burn mixture during the negative valve overlap period had a large effect on combustion phasing, due to localized heat release and the production of chemically reactive species. As the injection was retarded to the intake stroke, the charge cooling effect tended to slow down the autoignition process. However, further retard of fuel injection to the compression stroke caused the earlier start of main combustion as fuel stratification was produced in the cylinder. In order to optimize the engine performance and engine-out emissions, double injection was investigated by injecting part of the fuel first in the negative valve overlap period and the rest of fuel during the intake or compression strokes. By varying the fueling of each injection, the best engine performance was obtained with the 50/50 fuel injection split ratio, while the lowest total NOx and soot emissions were seen with the optimal split injection ratio of 10/90

Discovery and Identification of W' and Z' in SU(2) x SU(2) x U(1) Models at the LHC

We explore the discovery potential of W' and Z' boson searches for various SU(2) x SU(2) x U(1) models at the Large Hadron Collider (LHC), after taking into account the constraints from low energy precision measurements and direct searches at both the Tevatron (1.96 TeV) and the LHC (7 TeV). In such models, the W' and Z' bosons emerge after the electroweak symmetry is spontaneously broken. Two patterns of the symmetry breaking are considered in this work: one is SU(2)_L x SU(2)_2 x U(1)_X to SU(2)_L x U(1)_Y (BP-I), another is SU(2)_1 x SU(2)_2 x U(1)_Y to SU(2)_L x U(1)_Y (BP-II). Examining the single production channel of W' and Z' with their subsequent leptonic decays, we find that the probability of detecting W' and Z' bosons in the considered models at the LHC (with 14 TeV) is highly limited by the low energy precision data constraints. We show that observing Z' alone, without seeing a W', does not rule out new physics models with non-Abelian gauge extension, such as the phobic models in BP-I. Models in BP-II would predict the discovery of degenerate W' and Z' bosons at the LHC.Comment: 29 pages, including 11 figures, 3 tables, added references for introductio

Real-time Data Flow Control for CBM-TOF Super Module Quality Evaluation

Super module assembled with MRPC detectors is the component unit of TOF (Time of Flight) system for the Compressed Baryonic Matter (CBM) experiment. Quality of super modules needs to be evaluated before it is applied in CBM-TOF. Time signals exported from super module are digitalized at TDC (Time to Digital Converter) station. Data rate is up to 6 Gbps at each TDC station, which brings a tremendous pressure for data transmission in real time. In this paper, a real-time data flow control method is designed. In this control method, data flow is divided into 3 types: scientific data flow, status data flow and control data flow. In scientific data flow, data of each TDC station is divided into 4 sub-flows, and then is read out by a parallel and hierarchical network, which consists of multiple readout mother boards and daughter boards groups. In status data flow, status data is aggregated into a specific readout mother board. Then it is uploaded to DAQ via readout daughter board. In control data flow, control data is downloaded to all circuit modules in the opposite direction of status data flow. Preliminary test result indicated data of STS was correctly transmitted to DAQ with no error and three type data flows were control orderly in real time. This data flow control method can meet the quality evaluation requirement of supper module in CBM-TOF

Productivity Measure in Using Enterprise Resource Planning System in Selected Companies in Beijing, China

With the globalization of economic development and social development, the business environment of enterprises has changed. Only by continuously improving the digital level and management level of enterprises can they survive in the fierce global competition and develop. In this economic and social environment, enterprise managers need to implement Enterprise Resource Planning (ERP) system in order to better operate and manage enterprise business and improve enterprise operating profit. Its purpose is to standardize and restructure enterprise process, financial process, capital flow and information flow, and improve enterprise operation ability, profitability and growth ability. The implementation of ERP system will have an impact on the level of enterprise productivity. Therefore, taking manufacturing companies as the research object, it is of great significance to explore the impact of ERP system implementation on the level of enterprise productivity.Taking the manufacturing companies selected in Beijing, China as the research object, this paper uses the method of combining theoretical analysis and empirical research to study the impact of ERP system on enterprise productivity and enterprise performance, so as to improve the industry’s understanding of ERP system. This paper uses data statistics and empirical research methods to analyze the impact of ERP system on enterprise productivity and enterprise performance. Firstly, it introduces the background and significance of the research, and then reviews and combs the relevant literature at home and abroad on ERP system, enterprise performance and the impact of ERP system on enterprise performance; Based on management information system theory, business process reengineering theory and financial performance theory, financial performance is measured from three aspects: operation ability, profitability and growth ability. Reasonably select relevant indicators to build the index system. This paper selects the enterprise financial data of Beijing manufacturing company implementing ERP system from 2013 to 2015, and uses the data model to make an empirical analysis on the impact of manufacturing company implementing ERP system on enterprise productivity and enterprise performance. It is found that in China, the implementation of ERP system by Beijing manufacturing company will have a certain impact on enterprise productivity and enterprise performance Combined with the principle of ERP, this paper discusses the impact of ERP Implementation on enterprise performance. In the empirical research part, descriptive statistics and Wilcoxon paired rank sum test are used to verify the impact of ERP Implementation on enterprise performance. The results show that the implementation of ERP system will improve the operation ability, profitability and growth ability of enterprises. Therefore, when preparing for the ERP system, enterprises must do a full feasibility and demand analysis to ensure the smooth implementation of the ERP system. Finally, this paper gives some suggestions on the impact of ERP Implementation on enterprise performance