SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new stat...SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new statistical distribution model exclusively used for LOS environment is proposed based on investigation of the experimental data. By reducing the number of the visible random arriving clusters,the model itself and the parameters estimating of the corresponding model are simplified in comparison with SV/IEEE 802.15.3a model. The simulation result indicates that the proposed model is more accurate in modeling small-scale LOS environment than SV/IEEE 802.15.3a model when considering cumulative distribution functions (CDFs) for the three key channel impulse response (CIR) statistics.展开更多
AIM: To assess the effectiveness of minimally invasive versus traditional open surgical approach in the treatment of Zenker diverticulum. METHODS: Between 1976 and 2006, 297 patients underwent transoral stapling (n = ...AIM: To assess the effectiveness of minimally invasive versus traditional open surgical approach in the treatment of Zenker diverticulum. METHODS: Between 1976 and 2006, 297 patients underwent transoral stapling (n = 181) or stapled diverticulectomy and cricopharyngeal myotomy (n = 116). Subjective and objective evaluations of the outcome of the two procedures were made at 1 and 6 mo after operation, and then every year. Long-term follow-up data were available for a subgroup of patients at a minimum of 5 and 10 years. RESULTS: The operative time and hospital stay were markedly reduced in patients undergoing the endosurgical approach. Overall, 92% of patients undergoing the endosurgical approach and 94% of those undergoing the open approach were symptom-free or were significantly improved after a median follow-up of 27 and 48 mo, respectively. At a minimum follow-up of 5 and 10 years, most patients were asymptomatic after both procedures, except for those individuals undergoing an endosurgical procedure for a small diverticulum (< 3 cm). CONCLUSION: Both operations relieve the outflow obstruction at the pharyngoesophageal junction, indicating that cricopharyngeal myotomy has an important therapeutic role in this disease independent of the resection of the pouch and of the surgical approach. Diverticula smaller than 3 cm represent a formal contraindication to the endosurgical approach because the common wall is too short to accommodate one cartridge of staples and to allow complete division of the sphincter.展开更多
Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recover...Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recovery ventilator and to investigate the effect of the air supply arrangement. Three types of mixing ventilation are chosen for the analysis of coupling ANSYS/FLUENT （a computational fluid dynamics （CFD） program） with TRNSYS （a building energy simulation （BES） software）. The adoption of mutual complementary boundary conditions for CFD and BES provides more accurate and complete information of indoor air distribution and thermal performance in buildings. A typical office-space situated in a middle storey is chosen for the analysis. The office-space is equipped with air-conditioners on the ceiling. A heat recovery ventilation system directly supplies flesh air to the office space. Its thermal performance and indoor air distribution predicted by the coupled method are compared under three types of ventilation system. When the supply and return openings for ventilation are arranged on the ceiling, there is no critical difference between the predictions of the coupled method and BES on the energy consumption of HVAC because PID control is adopted for the supply air temperature of the occupied zone. On the other hand, approximately 21% discrepancy for the heat recovery estimation in the maximum between the simulated results of coupled method and BES-only can be obviously found in the floor air supply ventilation case. The discrepancy emphasizes the necessity of coupling CFD with BES when vertical air temperature gradient exists. Our future target is to estimate the optimum design of heat recovery ventilation system to control CO2 concentration by adjusting flow rate of flesh air.展开更多
基金the Key Program of National Natural Science Foundation of China(Grant No.60432040).
文摘SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new statistical distribution model exclusively used for LOS environment is proposed based on investigation of the experimental data. By reducing the number of the visible random arriving clusters,the model itself and the parameters estimating of the corresponding model are simplified in comparison with SV/IEEE 802.15.3a model. The simulation result indicates that the proposed model is more accurate in modeling small-scale LOS environment than SV/IEEE 802.15.3a model when considering cumulative distribution functions (CDFs) for the three key channel impulse response (CIR) statistics.
文摘AIM: To assess the effectiveness of minimally invasive versus traditional open surgical approach in the treatment of Zenker diverticulum. METHODS: Between 1976 and 2006, 297 patients underwent transoral stapling (n = 181) or stapled diverticulectomy and cricopharyngeal myotomy (n = 116). Subjective and objective evaluations of the outcome of the two procedures were made at 1 and 6 mo after operation, and then every year. Long-term follow-up data were available for a subgroup of patients at a minimum of 5 and 10 years. RESULTS: The operative time and hospital stay were markedly reduced in patients undergoing the endosurgical approach. Overall, 92% of patients undergoing the endosurgical approach and 94% of those undergoing the open approach were symptom-free or were significantly improved after a median follow-up of 27 and 48 mo, respectively. At a minimum follow-up of 5 and 10 years, most patients were asymptomatic after both procedures, except for those individuals undergoing an endosurgical procedure for a small diverticulum (< 3 cm). CONCLUSION: Both operations relieve the outflow obstruction at the pharyngoesophageal junction, indicating that cricopharyngeal myotomy has an important therapeutic role in this disease independent of the resection of the pouch and of the surgical approach. Diverticula smaller than 3 cm represent a formal contraindication to the endosurgical approach because the common wall is too short to accommodate one cartridge of staples and to allow complete division of the sphincter.
基金Project supported by Grant-in-Aid for Scientific Research (JSPS KAKENHI for Young Scientists (S), 21676005)
文摘Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recovery ventilator and to investigate the effect of the air supply arrangement. Three types of mixing ventilation are chosen for the analysis of coupling ANSYS/FLUENT （a computational fluid dynamics （CFD） program） with TRNSYS （a building energy simulation （BES） software）. The adoption of mutual complementary boundary conditions for CFD and BES provides more accurate and complete information of indoor air distribution and thermal performance in buildings. A typical office-space situated in a middle storey is chosen for the analysis. The office-space is equipped with air-conditioners on the ceiling. A heat recovery ventilation system directly supplies flesh air to the office space. Its thermal performance and indoor air distribution predicted by the coupled method are compared under three types of ventilation system. When the supply and return openings for ventilation are arranged on the ceiling, there is no critical difference between the predictions of the coupled method and BES on the energy consumption of HVAC because PID control is adopted for the supply air temperature of the occupied zone. On the other hand, approximately 21% discrepancy for the heat recovery estimation in the maximum between the simulated results of coupled method and BES-only can be obviously found in the floor air supply ventilation case. The discrepancy emphasizes the necessity of coupling CFD with BES when vertical air temperature gradient exists. Our future target is to estimate the optimum design of heat recovery ventilation system to control CO2 concentration by adjusting flow rate of flesh air.
