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[en] The hydraulic free-piston engine integrates the internal combustion engine with a hydraulic pump. The piston of an HFPE is not connected to the crankshaft and the piston movement is determined by the forces that act upon it. These features optimize combustion and make higher power density and efficiency increase. In this paper, a detailed thermodynamic and energy saving analysis is performed to demonstrate the fundamental efficiency advantage of an HFPE. The thermodynamic results show that the combustion process can be optimized to an ideal engine cycle. The experimental results show that the HFPE combustion process is a nearly constant-volume process; the efficiency is approximately 50%; the piston displacement and velocity curves for a cycle are the same at any frequency, even at a 1.25 Hz. The maximum velocities are of the same value at high or low frequencies. Similarly, pump output flow is not influenced by frequency. The independent cyclic characteristics of HFPE determine that it should work in higher frequencies when the vehicle runs in Japanese 10–15 road conditions. It indicates that a higher working frequency will lead to the starting frequency of HFPE, and a lower frequency will decrease the pressurized pressure of the hydraulic accumulator. - Highlights: • The thermodynamic and energy saving benefits of the HFPEs was investigated. • The approach of combustion optimization was obtained by adjusting the injection timing and compression ratio. • The high efficiency area of HFPE was given as a function of injection timing and compression pressure. • The maximum efficiency of HFPE of 50% was obtained from the prototype. • The method of energy saving with adjusting the piston frequency was examined.
[en] Highlights: • A hydraulic electronic unit injector in HFPE is developed and the test bench is established. • Effect of drive pressure on injection delay of hydraulic electronic unit injector are investigated. • Cycle fuel injection quantity is tested online and off-line engine operation. • The BDC control results in HFPE based on feed-forward compensation are acceptable. • The energy flow in HFPE is analyzed and the hydraulic output energy is optimized. - Abstract: The fuel injection system in two stroke engine is very important, therefore the hydraulic electronic unit injector system is developed and the injection characteristics of hydraulic electronic unit injector are investigated. Firstly the HFPE and the hydraulic electronic unit injector working principle are analyzed, and then PID control strategy is built by engine demand. In order to validate the feasibility of hydraulic electronic unit injector, the prototype test bench is established. The specific measurement principle is presented. Further the injection characteristics, such as the effect of injection pressure on injection delay and the effect of engine frequency on injection delay, are analyzed. In order to optimize the engine stability performance, the BDC control based on fuel injection control is investigated. The load control based on fuel injection is also discussed and the BDC feedforward control with the load variation is investigated. Experiment results of stead engine operation shows that the hydraulic electronic unit injector system based on PID control can be satisfied with the engine operation demand. In addition, cycle fuel injection quantity is tested online and off-line engine operation. It is obvious that the fuel injection quantity is affected by the hydraulic pressure. The fuel injection quantity variation can be improved with decreasing the fluctuation of drive pressure or adopting more suitable oil common rail instead of connected with exhaust valve hydraulic drive oil-way. The energy flow in HFPE is analyzed and the hydraulic output energy can be optimized by selecting suitable hydraulic valves parameters. The fuel injection quantity should be designed by the energy balance and the stable operation requirement in spite of the higher thermal efficiency.
[en] The cold start characteristic of hydraulic free piston diesel engine may affect its stable operation. Therefore the specific cold start characteristics, such as BDC or TDC positions, pressure in-cylinder, heat release rate, should be investigated in detail. These parameters fluctuate in some regularity in the cod start process. With the development of the free piston engine prototype and the establishment of test bench, the results are obtained. For the dynamic results, the fluctuation range of TDC and BDC positions is 8 mm and decreases with time. The thermodynamic results show that the combustion process is not stable and the pressure in-cylinder fluctuates largely in the cold start process. In addition, the combustion is rapid and knock happens inevitably. In order to investigate the reasons, a CFD model is established for temperature analysis in-cylinder and heat transfer conditions. It is found that higher start wall temperature will lead to more uniform temperature distribution. The delay period may decreases and heat release will move forward. This reason is analyzed by thermodynamic derivation based on the first law of thermodynamics. Finally, the improvement suggestions of cold start strategy are proposed. - Highlights: • The cold start behaviors of HFPE are investigated in detail. • CFD method is used for simulating temperature distribution in start process. • Thermodynamic derivation uncovers the compression temperature distribution. • The improvement suggestions of cold start strategy are proposed.
[en] Objective: To evaluate the relation between shunt index (SI) and caliber of stent using via rectum 99mTcO4- portal vein scintigraphy and to observe the influence of TIPSS on hepatic hemodynamics. Methods: Nineteen health hybrid dogs were selected to make the model of portal hypertension. 99mTcO4- was infused via rectum before and after Tips and SI and RI of heart and liver were measured. Relation of SI and the caliber of stent was calculated by dispose of statistics. Results: SI positively correlated with caliber of stent; the regression equation was: Y = 0.301 + 0.221X, and correlation coefficient was 0.985, P < 0.05 after t-test. RI ratio of heart/liver (H/L) increased when shunt tract became shut or narrow after TIPSS operation. Conclusion: Stent of 10 mm diameter was chosen on condition that SI was above 40%. When SI was between 30%-40%, the 8 mm diameter stent would be chosen. SI was under 30%, 6 mm diameter stent would be chosen, 99mTcO4- portal vein scintigraphy may check close or open of the shunt tract after TIPSS
[en] Objective: Through a comparative analysis serum concentration of DDP administrated by intra-arterial injection and intravenous infusion in patients with non-small cell lung cancer (NSCLC), the whole body toxic reactions and the pharmacological mechanism of chemotherapy agents administrated by bronchial artery infusion (BAI) was studied. Methods: In total 60 patients with advanced NSCLC confirmed by pathology were randomly enrolled into two groups in this study. The 30 patients in group A were treated by BAI chemotherapy with DDP at the dose of 80 mg/m2 within 30 min, while MMC at the dose of 10 mg/m2 and VDS at the dose of 3 mg/m2 were given intravenously. Patients in group B was given intravenous chemotherapy of the same components as that given in group A. Blood samples was collected at 5 min, 15 min, 30 min, 1h, 2h, 4h, 8h, 24h and 48h from the beginning of DDP infusion. High performance liquid chromatography (HPLC) was used to measure DDP concentration in blood samples and a time-concentrate curve was drawn. During chemotherapy, the side-effects were investigated. Results: (1) Both group A and B reached a peak concentration at 30 min. Peak concentration value of group B is higher than that of group A. There was a statistical difference of peak concentration between group A and B (P<0.001). (2) AUC value of group B is higher than that of group A, with a statistical difference (P<0.05). (3) The incidence of gastrointestinal complication and kidney function damage has a statistical difference between group A and B (P=0.002 and 0.028 respectively). Conclusion: The side-effects is slighter in BAI chemotherapy than in IV chemotherapy in the treatment of NSCLC
[en] Objective: To explore the clinical value of seeds implantation technique under CT guidance, combined with internal iliac arterial infusion chemotherapy in the treatment of recurrence pelvic tumors. Methods: Eight patients with recurrence pelvic tumors have been treated by 125I seeds implant combined with internal iliac arterial infusion chemotherapy. The chemotherapy scheme was based on the primary tumor type. Under CT guidance, 125I seeds were implanted into the pelvic tumors according to TPS or Halarism's experienced function: mCi = Da x 5 (Da means the average of length, width and height of the lesion). mCi is the total activity of 125I. The number of 125I seeds needed equals to that of total activities divided by the activity of single particle. Results: All the patients received PET-CT chest follow up two months later. CR, PR, NC, PD were abtained in 0, 5, 2, 1 cases respectively. Two patients died within one year, other 6 patients are still alive, the longest survival period was more than 15 months, the 1-year survival rates was 75%. Conclusions: 125I seeds implant combined with internal iliac arterial infusion chemotherapy is an effective method in the treatment of pelvic recurrence tumors. (authors)
[en] Objective: To evaluate the the intra-arterial chrono-chemotherapy of liver metastasis from colorectal cancer. Methods: From May 2002 to April 2003, 22 patients were enrolled in this study, who were suffering from liver metastases from colorectal cancer. They were assigned to group A (control group, intra-arterial constant rate infusion, 10 patients) and group B (therapeutic group, intra-arterial chrono-chemotherapy, 12 patients). The toxic effects and the clinical effects of the chemotherapy were evaluated according to the criteria from WHO. Results: There is a significant difference between the two groups on morbidity of mucositis, severe nausea and vomiting. On the short term result, there was no significant difference between the two groups. Conclusion: The intra-arterial chrono-chemotherapy has a better acceptance than the intra-arterial constant rate infusion, which is an effective treatment of the liver metastases from the colorectal cancer
[en] Objective: To investigate the clinical value of CT guided radioactive seed 125I implantation in treating hilar hepatic tumor and metastatic lymph nodes. Methods: 32 patients with pancreatic cancer accepted CT guided radioactive seeds 125I implantation were enrolled in this study. The average tumor dimension was 4.2 cm. In this series, there were 8 cases of hepatocellular carcinoma, 12 cases of hilar cholangio carcinoma, 6 cases of hepatic metastasis and 6 of hepatic hilar tumor and metastatic lymph nodes. Among these patients, 14 cases had cholangiectasis and 22 cases had cirrhosis. Under CT guidance, 125I seeds of 0.6-0.9 mCi were implanted into the pancreatic cancer at a distance of 1.0-1.5 cm according to TPS. Results: Two cases died on account of metastasis and three died through liver function failure. Among CT followed-up of 32 patients in 2 months, 2 obtained CR, 20 obtained PR, 5 NC and 5 PD. The responsive rate was 68.8%. The side effects occurred during the procedure including pneumothorax in 1 case with lung compression less than 30%; 7 seeds migration in liver and 3 seeds in lung. WBC decreased slightly in 1 cases during 2 months follow up. No massive bleeding, biliary fistula, intestinal fistula, intestinal hemorrhage, acute pancreatitis, enterorrhagia and intra-abdominal abscess were encountered. Conclusions: CT guided radioactive seed 125I implantation procedure is a safe and effective method in treating hilar hepatic tumor and metastatic lymph nodes with good clinical effects of minimal damage and few complications. (authors)
[en] Objective: To analyze the local therapeutic efficacy, side effect , and complication of 46 patients with liver metastasis caused by nasopharyngeal carcinoma treated by comprehensive interventional therapy. Methods: TACE was performed on 32 tumors in 17 patients under the guidance of DSA; RFA was performed on 61 tumors in 29 patients under the guidance of CT scanning. The results were evaluated by the double-phase CT scanning. Results: All the patients were effective during short term follow up, without severe complications. Conclusions: Comprehensive interventional therapy is safe, effective and reliable in the treatment of liver metastasis caused by nasopharyngeal carcinoma. (authors)
[en] Objective: To determine the sensitivity of fluorodeoxyglucose positron emission tomography/computerized tomography (18F-FDG-PET/CT) for detecting the residual HCC after interventional therapy and to analyze the lipiodol-accumulated and lipiodol-unaccumulated fields for localization of the residual tumor; together with exploration of field for 18F-FDG-PET/CT in interventional therapy. Methods: 22 HCC patients with average lesion diameter 8.1 cm received 18F-FDG-PET/CT examination after transcatheter hepatic arterial chemoembolization (TACE) or the treatment of TACE following radiofrequency ablation (RFA). The findings of relation between residual and lipiodol-accumulated field could lead to perform more interventional therapy for the residual under PET-CT guidance. For patients with negative finding should be followed up with imaging examination and alpha-fetoprotein (AFP) for the sexclusion. Results: The lesions of 21 cases showed more or less lipiodol deposition, including 3 cases with 18F-FDG-PET/CT scanning after TACE which showed tracer concentrations indicating the existence of the residuals in the lipiodol-accumulated and lipiodol-unaccumulated fields. 18 cases received 18F-FDG-PET/CT scanning after TACE following RFA showed residuals in 11. The residuals in 9 of the 11 cases distributed in the region of lipiodol-accumulated and lipiodol-unaccumulated fields and the residuals of the rest 2 cases only occurred in the lipiodol-unaccumulated area. The imagings of 18F-FDG-PET/CT scanning for 9 cases were negative, but with falsenegative in 1 case. After all the sensitivity of 18F-FDG-PET/CT scanning was 93.3%. Moreover, another 5 cases with residual lesions achieved local radical therapy after RFA under 18F-FDG-PET/CT guidance. Conclusions: 18F-FDG PET/CT has higher sensitivity for the detection of residuals of large HCC after interventional therapy. Residuals might exist in lipiodol-accumulated or lipiodol-unaccumulated fields and therefore 18F-FDG PET/CT may provide the assessment for the therapeutic effect of HCC after interventional therapy and guidance for more treatments. (authors)