Variable-voltage variable-frequency drives have been widely adopted by building services engineers in the area of HVAC （heating, ventilation and air conditioning） applications and became the substantial energy consu...Variable-voltage variable-frequency drives have been widely adopted by building services engineers in the area of HVAC （heating, ventilation and air conditioning） applications and became the substantial energy consumption in both commercial and residential buildings. Since the speed of a compressor driven by a conventional TPIM （two-phase induction motor） is fixed, it is either switched ＂ON＂, working at maximum capacity or switched ＂OFF＂ by a thermostat. While the most recent VF （variable-frequency） reluctance motor driven compressor delivers an enhanced performance over TPIM drive, it also provides variable-speed operation as the temperature changes, while improving the overall energy efficiency. This paper aimed to evaluate the performance of both TPIM and VF compressor drives for single-phase residential air-conditioning applications. Their cooling performance and harmonic distortions will be investigated. International standards for harmonic limits will also be applied in evaluating the distortions created by the VF drive.展开更多
Objective:To observe the clinical effects of the combined use of acupuncture and herbal medicine for treatment of chloasma.Methods:Totally 60 patients were randomly divided into a treatment group of 30 cases,treated b...Objective:To observe the clinical effects of the combined use of acupuncture and herbal medicine for treatment of chloasma.Methods:Totally 60 patients were randomly divided into a treatment group of 30 cases,treated by acupuncture and herbal medicine,and a control group of 30 cases,administered Vitamin C and Vitamin E.The clinical effects were observed.Results:The total effective rate of the treatment group is 93.3%better than that of the control group(76.7%) ,the difference was significant(P<0.01) .Conclusion:Combined use of acupuncture and herbal medicine may yield definite therapeutic effects in treating chloasma patients.展开更多
The need to maintain high rice yields and improve fertilizer nitrogen(N)-use efficiency has fueled the use of tools such as leaf colour chart(LCC) and chlorophyll meter(SPAD meter) in managing fertilizer N based on co...The need to maintain high rice yields and improve fertilizer nitrogen(N)-use efficiency has fueled the use of tools such as leaf colour chart(LCC) and chlorophyll meter(SPAD meter) in managing fertilizer N based on colour of the leaf. Field experiments were conducted during 2011 to 2013 at Ludhiana, India to assess the need for basal N application and to establish critical threshold values of leaf greenness as measured by LCC and SPAD meter for formulating strategies for in-season management of fertilizer N in dry direct-seeded rice(DDSR). Avoiding application of N at sowing did not adversely affect rice grain yield, indicating that basal N application in DDSR was not necessary and might lead to reduced N-use efficiency. Monitoring N uptake rate during the growing season of DDSR suggested that N uptake rate peaked at the two growth stages: maximum tillering(42 to 56 days after sowing(DAS))and panicle initiation stages(70 to 84 DAS). Using the Cate-Nelson procedure, critical LCC and SPAD meter values for fertilizer N application worked out to be 4 and 37, respectively. Real-time fertilizer N management strategy based on applying 30 kg N ha-1whenever SPAD meter or LCC readings fell below the critical values maintained optimum rice yields along with higher N-use efficiency than that observed by following blanket recommendation for fertilizer N in the region. The fixed-time variable-dose strategy consisted of applying prescriptive doses of 20 kg N ha-1at 14 DAS and 30 kg N ha-1at 28 DAS and corrective doses of 30, 40 or 50 kg N ha-1at 49 and 70 DAS depending upon LCC shade to be ≥ 4, 4–3.5, or < 3.5 and SPAD meter readings to be ≥ 40, 40–35, or< 35, respectively. This strategy also resulted in optimal rice yield along with higher N-use efficiency as compared to the blanket recommendation. This study revealed that in DDSR, fertilizer N could be managed more efficiently using the tools of LCC and SPAD meter than the current blanket recommendation.展开更多
文摘Variable-voltage variable-frequency drives have been widely adopted by building services engineers in the area of HVAC （heating, ventilation and air conditioning） applications and became the substantial energy consumption in both commercial and residential buildings. Since the speed of a compressor driven by a conventional TPIM （two-phase induction motor） is fixed, it is either switched ＂ON＂, working at maximum capacity or switched ＂OFF＂ by a thermostat. While the most recent VF （variable-frequency） reluctance motor driven compressor delivers an enhanced performance over TPIM drive, it also provides variable-speed operation as the temperature changes, while improving the overall energy efficiency. This paper aimed to evaluate the performance of both TPIM and VF compressor drives for single-phase residential air-conditioning applications. Their cooling performance and harmonic distortions will be investigated. International standards for harmonic limits will also be applied in evaluating the distortions created by the VF drive.
文摘Objective:To observe the clinical effects of the combined use of acupuncture and herbal medicine for treatment of chloasma.Methods:Totally 60 patients were randomly divided into a treatment group of 30 cases,treated by acupuncture and herbal medicine,and a control group of 30 cases,administered Vitamin C and Vitamin E.The clinical effects were observed.Results:The total effective rate of the treatment group is 93.3%better than that of the control group(76.7%) ,the difference was significant(P<0.01) .Conclusion:Combined use of acupuncture and herbal medicine may yield definite therapeutic effects in treating chloasma patients.
基金supported by the Indian Council of Cultural Relations and Egypt Government through the Cultural Exchange Programme
文摘The need to maintain high rice yields and improve fertilizer nitrogen(N)-use efficiency has fueled the use of tools such as leaf colour chart(LCC) and chlorophyll meter(SPAD meter) in managing fertilizer N based on colour of the leaf. Field experiments were conducted during 2011 to 2013 at Ludhiana, India to assess the need for basal N application and to establish critical threshold values of leaf greenness as measured by LCC and SPAD meter for formulating strategies for in-season management of fertilizer N in dry direct-seeded rice(DDSR). Avoiding application of N at sowing did not adversely affect rice grain yield, indicating that basal N application in DDSR was not necessary and might lead to reduced N-use efficiency. Monitoring N uptake rate during the growing season of DDSR suggested that N uptake rate peaked at the two growth stages: maximum tillering(42 to 56 days after sowing(DAS))and panicle initiation stages(70 to 84 DAS). Using the Cate-Nelson procedure, critical LCC and SPAD meter values for fertilizer N application worked out to be 4 and 37, respectively. Real-time fertilizer N management strategy based on applying 30 kg N ha-1whenever SPAD meter or LCC readings fell below the critical values maintained optimum rice yields along with higher N-use efficiency than that observed by following blanket recommendation for fertilizer N in the region. The fixed-time variable-dose strategy consisted of applying prescriptive doses of 20 kg N ha-1at 14 DAS and 30 kg N ha-1at 28 DAS and corrective doses of 30, 40 or 50 kg N ha-1at 49 and 70 DAS depending upon LCC shade to be ≥ 4, 4–3.5, or < 3.5 and SPAD meter readings to be ≥ 40, 40–35, or< 35, respectively. This strategy also resulted in optimal rice yield along with higher N-use efficiency as compared to the blanket recommendation. This study revealed that in DDSR, fertilizer N could be managed more efficiently using the tools of LCC and SPAD meter than the current blanket recommendation.
