Diffusion couples,WC/Co-1at.%C,V8C7/Co,and WC/Co-0.3wt.%V8C7 were constructed and annealed at temperatures ranging from 1100 to 1300℃. The concentration profile of V and W atoms in these couples were measured by EPMA...Diffusion couples,WC/Co-1at.%C,V8C7/Co,and WC/Co-0.3wt.%V8C7 were constructed and annealed at temperatures ranging from 1100 to 1300℃. The concentration profile of V and W atoms in these couples were measured by EPMA. Aided by Thermo-calc ＆ DICTRA software package,the concentration profiles of W and V in established diffusion couples were calculated by the moving boundary model according to revised dynamic parameters and MOB database,respectively. Then the concentration profile of W in Co binder during sintering WC-Co cemented carbide was simulated by the Cell model. It can provide reference for composition and sintering process design of cemented carbides with high performance. Meanwhile,the validity of revised dynamic parameters of the W-C-Co-V system is verified by the comparison of experimental and simulated results.展开更多
AIM: To compare the new Olympus V-scope (VS) to conventional endoscopic retrograde cholangiopancreati-cography (ERCP). METHODS: Forty-nine patients with previous endoscopic papillotomy who were admitted for interventi...AIM: To compare the new Olympus V-scope (VS) to conventional endoscopic retrograde cholangiopancreati-cography (ERCP). METHODS: Forty-nine patients with previous endoscopic papillotomy who were admitted for interventional ERCP for one of several reasons were included in this single-centre, prospective randomized study. Consecutive patients were randomized to either the VS group or to the conventional ERCP group. ERCP-nave patients who had not undergone papillotomy were excluded. The main study parameters were interventional examination time, X-ray time and dose, and premedication dose (all given below as the median, range) and were investigated in addition to each patient's clinical outcome and complications. Subjective scores to assess each procedure were also provided by the physicians and endoscopy assistants who carried out the procedures. A statistical analysis was carried out using the Wilcoxon rank-sum test.RESULTS: Twenty-five patients with 50 interventions were examined with the VS ERCP technique, and 24 patients with 47 interventions were examined using the conventional ERCP technique. There were no significant differences between the two groups regarding the age, sex, indications, degree of ERCP difficulty, or interventions performed. The main study parameters in the VS group showed a nonsignificant trend towards a shorter interventional examination time (29 min, 5-50 min vs 31 min, 7-90 min, P = 0.28), shorter X-ray time (5.8 min, 0.6-14.1 min vs 6.1 min, 1.6-18.8 min, P = 0.48), and lower X-ray dose (1351 cGy/m2 , 159-5039 cGy/m2 vs 1296 cGy/m2 , 202.2-6421 cGy/m 2 , P = 0.34). A nonsignificant trend towards fewer adverse events occurred in the VS group as compared with the conventional ERCP group (cholangitis: 12% vs 16%, P = 0.12; pain: 4% vs 12.5%, P = 0.33; post-ERCP pancreatitis: 4% vs 12.5%, P = 0.14). In addition, there were no statistically significant differences in assessment by the physicians and endoscopy assistants using subjective questionnaires.CONCLUSION: ERCP using the short-guidewire V-system did not significantly improve ERCP performance or patient outcomes, but it may reduce and simplify the ERCP procedure in difficult settings.展开更多
The control system for the Experimental Advanced Superconductive Tokamak （EAST） cryogenic system is designed and constructed based on Delta-V DCS （Distribution Control System）, which consists of engineering workst...The control system for the Experimental Advanced Superconductive Tokamak （EAST） cryogenic system is designed and constructed based on Delta-V DCS （Distribution Control System）, which consists of engineering workstations, operator workstations, application workstations, redundant controller units, input/output （I/O） cards and a redundant control network. Our task is to design a supervisory and control system to provide the operator interface for control and monitoring, sending alarms, archiving of selected signals, and other routines to analyze realtime and historic data. The hardware configuration, software structure and control algorithms are illustrated in detail in this paper. Hvpothetic oroblems and further research are also mentioned.展开更多
A real-time operating system （RTOS）, also named OS, is designed based on the hardware platform of MC68376, and is implemented in the electronic control system for unit pump in diesel engine. A parallel and time-base...A real-time operating system （RTOS）, also named OS, is designed based on the hardware platform of MC68376, and is implemented in the electronic control system for unit pump in diesel engine. A parallel and time-based task division method is introduced and the multi-task software architecture is built in the software system for electronic unit pump （EUP） system. The V-model software development process is used to control algorithm of each task. The simulation results of the hardware-in-the-loop simulation system （HILSS） and the engine experimental results show that the OS is an efficient real-time kernel, and can meet the real-time demands of EUP system; The built multi-task software system is real-time, determinate and reliable. V-model development is a good development process of control algorithms for EUP system, the control precision of control system can be ensured, and the development cycle and cost are also decreased.展开更多
The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The p...The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2^+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.展开更多
We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems.The emission intensity I and Mandel＇s Q parameter show stochastic resonance with respect to the pure dephas...We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems.The emission intensity I and Mandel＇s Q parameter show stochastic resonance with respect to the pure dephasing constantγp.The amplitude fluctuation of the field causes these systems to lose their coherence.On the other hand,the amplitude fluctuation provides a new interference method for these systems.The quantum beats are shown in the orthogonal system.展开更多
基金the National Natural Science Foundation of China (No. 50471101)the Flan-ders-China Bilateral Project BIL 02/04.
文摘Diffusion couples,WC/Co-1at.%C,V8C7/Co,and WC/Co-0.3wt.%V8C7 were constructed and annealed at temperatures ranging from 1100 to 1300℃. The concentration profile of V and W atoms in these couples were measured by EPMA. Aided by Thermo-calc ＆ DICTRA software package,the concentration profiles of W and V in established diffusion couples were calculated by the moving boundary model according to revised dynamic parameters and MOB database,respectively. Then the concentration profile of W in Co binder during sintering WC-Co cemented carbide was simulated by the Cell model. It can provide reference for composition and sintering process design of cemented carbides with high performance. Meanwhile,the validity of revised dynamic parameters of the W-C-Co-V system is verified by the comparison of experimental and simulated results.
文摘AIM: To compare the new Olympus V-scope (VS) to conventional endoscopic retrograde cholangiopancreati-cography (ERCP). METHODS: Forty-nine patients with previous endoscopic papillotomy who were admitted for interventional ERCP for one of several reasons were included in this single-centre, prospective randomized study. Consecutive patients were randomized to either the VS group or to the conventional ERCP group. ERCP-nave patients who had not undergone papillotomy were excluded. The main study parameters were interventional examination time, X-ray time and dose, and premedication dose (all given below as the median, range) and were investigated in addition to each patient's clinical outcome and complications. Subjective scores to assess each procedure were also provided by the physicians and endoscopy assistants who carried out the procedures. A statistical analysis was carried out using the Wilcoxon rank-sum test.RESULTS: Twenty-five patients with 50 interventions were examined with the VS ERCP technique, and 24 patients with 47 interventions were examined using the conventional ERCP technique. There were no significant differences between the two groups regarding the age, sex, indications, degree of ERCP difficulty, or interventions performed. The main study parameters in the VS group showed a nonsignificant trend towards a shorter interventional examination time (29 min, 5-50 min vs 31 min, 7-90 min, P = 0.28), shorter X-ray time (5.8 min, 0.6-14.1 min vs 6.1 min, 1.6-18.8 min, P = 0.48), and lower X-ray dose (1351 cGy/m2 , 159-5039 cGy/m2 vs 1296 cGy/m2 , 202.2-6421 cGy/m 2 , P = 0.34). A nonsignificant trend towards fewer adverse events occurred in the VS group as compared with the conventional ERCP group (cholangitis: 12% vs 16%, P = 0.12; pain: 4% vs 12.5%, P = 0.33; post-ERCP pancreatitis: 4% vs 12.5%, P = 0.14). In addition, there were no statistically significant differences in assessment by the physicians and endoscopy assistants using subjective questionnaires.CONCLUSION: ERCP using the short-guidewire V-system did not significantly improve ERCP performance or patient outcomes, but it may reduce and simplify the ERCP procedure in difficult settings.
基金The project supported by the National Meg-science Engineering Project of the Chinese Government
文摘The control system for the Experimental Advanced Superconductive Tokamak （EAST） cryogenic system is designed and constructed based on Delta-V DCS （Distribution Control System）, which consists of engineering workstations, operator workstations, application workstations, redundant controller units, input/output （I/O） cards and a redundant control network. Our task is to design a supervisory and control system to provide the operator interface for control and monitoring, sending alarms, archiving of selected signals, and other routines to analyze realtime and historic data. The hardware configuration, software structure and control algorithms are illustrated in detail in this paper. Hvpothetic oroblems and further research are also mentioned.
文摘A real-time operating system （RTOS）, also named OS, is designed based on the hardware platform of MC68376, and is implemented in the electronic control system for unit pump in diesel engine. A parallel and time-based task division method is introduced and the multi-task software architecture is built in the software system for electronic unit pump （EUP） system. The V-model software development process is used to control algorithm of each task. The simulation results of the hardware-in-the-loop simulation system （HILSS） and the engine experimental results show that the OS is an efficient real-time kernel, and can meet the real-time demands of EUP system; The built multi-task software system is real-time, determinate and reliable. V-model development is a good development process of control algorithms for EUP system, the control precision of control system can be ensured, and the development cycle and cost are also decreased.
文摘The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2^+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.
基金supported by the National Natural Science Foundation of China(Grand Nos.91021009,21073110,and 11374191)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2013AQ020)+1 种基金the Postdoctoral Science Foundation of China(Grant No.2013M531584)the Doctoral Program of Higher Education of China(Grant Nos.20130131110005 and 20130131120006)
文摘We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems.The emission intensity I and Mandel＇s Q parameter show stochastic resonance with respect to the pure dephasing constantγp.The amplitude fluctuation of the field causes these systems to lose their coherence.On the other hand,the amplitude fluctuation provides a new interference method for these systems.The quantum beats are shown in the orthogonal system.
