This study presents the thermal comfort and hygrothermal performance of building envelope of the first certified passive single-family detached house in Estonia.Temperature and humidity conditions were measured from d...This study presents the thermal comfort and hygrothermal performance of building envelope of the first certified passive single-family detached house in Estonia.Temperature and humidity conditions were measured from different rooms and building envelopes.This article presents analysis of measurement results during the first year after construction.Results showed high room temperature,achieved mainly due to large windows with southern exposure and the small heat loss of the building envelope.High indoor temperature decreased the indoor RH(relative humidity)to quite low levels.Even the RH was low,the moisture excess was high indicating that the design of PH(passive houses)indoor humidity loads cannot be decreased.Humidity in the externally insulated cross-laminated timber panels was observed to be high,caused by drying out of the constructional moisture and the high diffusion resistance of the wood fibre sheathing board.That caused water vapour condensation and risk for mould growth.In conclusion,while planning buildings with high-energy efficiency,more focused attention should be paid to the performance of the building service systems and moisture safety already in the preliminary stages of design.展开更多
Threshing is one of the most critical parts of post-harvest operation which affects the quality and quantity of maize production.It could be done manually or mechanically.However,the objective of this study was to eva...Threshing is one of the most critical parts of post-harvest operation which affects the quality and quantity of maize production.It could be done manually or mechanically.However,the objective of this study was to evaluate the performance of a maize cob thresher fabricated at National Centre for Agricultural Mechanization(NCAM)Ilorin at three different moisture contents and analyze the result using ANOVA and bar chart as statistical tools.The average values of parameters evaluated at three different stages of moisture content(15.81%,16.79%and 17.10%)of maize cob are as follow:threshing capacity 754.20,737.38 and 720.23 kg/h;threshing efficiency 99.73%,99.63%and 99.16%;cleaning efficiency 89.82%,89.45%and 88.34%;broken grains ratio 0.84%,0.79%and 0.70%;time taken 43,44 and 45 s,respectively.The total amount of maize cob fed into the machine was 9 kg in three replicates for each of the moisture content and the average values of threshed maize of 8.08,8.05 and 7.95 kg was recovered,respectively.There was significant difference in threshing efficiency,amount of chaffs in the threshed maize and the percentage broken ration.At 17.10%moisture content,the percentage broken grain ratio was minimal.At high moisture content,more force,energy and time is required to thresh certain amount of maize cob.Also,at minimal moisture content less force and energy is required for maximum output.Therefore,considering the previous work on performance evaluation of maize cob thresher,this machine performed satisfactorily and is far better than manual method.The machine is effective,efficient,affordable and available for the small and medium scale farmers in Nigeria.展开更多
A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge...A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge disintegration can destroy the sludge structure and cell wall, so as change the sludge floc structure and moisture distribution, thus affecting the dewatering performance of sludge. In this article, the disintegration methods were ultrasound treatment, K2 Fe O4oxidation and KMn O4 oxidation. The degree of disintegration（DDCOD）, sludge moisture distribution and the final water content of sludge cake after centrifuging were measured. Results showed that three disintegration methods were all effective, and K2 Fe O4oxidation was more efficient than KMn O4 oxidation. The content of free water increased obviously with K2 Fe O4and KMn O4 oxidations, while it decreased with ultrasound treatment. The changes of free water and interstitial water were in the opposite trend. The content of bounding water decreased with K2 Fe O4oxidation, and increased slightly with KMn O4 oxidation, while it increased obviously with ultrasound treatment. The water content of sludge cake after centrifuging decreased with K2 Fe O4oxidation, and did not changed with KMn O4 oxidation, but increased obviously with ultrasound treatment. In summary, ultrasound treatment deteriorated the sludge dewaterability, while K2 Fe O4and KMn O4 oxidation improved the sludge dewaterability.展开更多
Steel and rubber are two kinds of materials which are often used for the tracks of off-road vehicles.The objective of this study was to compare tractive performances of steel and rubber grouser shoes under different s...Steel and rubber are two kinds of materials which are often used for the tracks of off-road vehicles.The objective of this study was to compare tractive performances of steel and rubber grouser shoes under different soil moisture contents.In this study,the tractive performance of single grouser shoe was predicted by soil parameters and three-dimensional shearing model.The soil used in this study was clay soil,and ten different soil moisture contents ranged from 8.58%to 54.36%were applied for investigation of soil parameters.For each soil moisture content,the penetration test,direct shearing test,density and soil moisture content measurement have been performed to obtain the required soil parameters.The experimental results showed that thrust and running resistance of steel single grouser shoe had similar trends to those of rubber single grouser shoe.The thrust of rubber single grouser shoe was always greater than that of steel single grouser shoe with the increase of soil moisture content,and as well as the running resistance.However,the traction of rubber single grouser shoe had a different trend to that of steel single grouser shoe.The traction of steel single grouser shoe was always greater than that of rubber single grouser shoe at any given moisture content except at the stage of less than 15%moisture content.From the experimental results,it can be concluded that the steel single grouser shoe performed better than rubber single grouser shoe in traction for the soil used in this study.展开更多
基金supported by the European Union through the European Regional Development Fundthe“Reducing the Environmental Impact of Buildings through Improvements of Energy Performance,AR12059”(financed by SA Archimedes)IUT1-15 project“Nearly-Zero Energy Solutions and Their Implementation on Deep Renovation of Buildings”(financed by the Estonian Research Council).
文摘This study presents the thermal comfort and hygrothermal performance of building envelope of the first certified passive single-family detached house in Estonia.Temperature and humidity conditions were measured from different rooms and building envelopes.This article presents analysis of measurement results during the first year after construction.Results showed high room temperature,achieved mainly due to large windows with southern exposure and the small heat loss of the building envelope.High indoor temperature decreased the indoor RH(relative humidity)to quite low levels.Even the RH was low,the moisture excess was high indicating that the design of PH(passive houses)indoor humidity loads cannot be decreased.Humidity in the externally insulated cross-laminated timber panels was observed to be high,caused by drying out of the constructional moisture and the high diffusion resistance of the wood fibre sheathing board.That caused water vapour condensation and risk for mould growth.In conclusion,while planning buildings with high-energy efficiency,more focused attention should be paid to the performance of the building service systems and moisture safety already in the preliminary stages of design.
文摘Threshing is one of the most critical parts of post-harvest operation which affects the quality and quantity of maize production.It could be done manually or mechanically.However,the objective of this study was to evaluate the performance of a maize cob thresher fabricated at National Centre for Agricultural Mechanization(NCAM)Ilorin at three different moisture contents and analyze the result using ANOVA and bar chart as statistical tools.The average values of parameters evaluated at three different stages of moisture content(15.81%,16.79%and 17.10%)of maize cob are as follow:threshing capacity 754.20,737.38 and 720.23 kg/h;threshing efficiency 99.73%,99.63%and 99.16%;cleaning efficiency 89.82%,89.45%and 88.34%;broken grains ratio 0.84%,0.79%and 0.70%;time taken 43,44 and 45 s,respectively.The total amount of maize cob fed into the machine was 9 kg in three replicates for each of the moisture content and the average values of threshed maize of 8.08,8.05 and 7.95 kg was recovered,respectively.There was significant difference in threshing efficiency,amount of chaffs in the threshed maize and the percentage broken ration.At 17.10%moisture content,the percentage broken grain ratio was minimal.At high moisture content,more force,energy and time is required to thresh certain amount of maize cob.Also,at minimal moisture content less force and energy is required for maximum output.Therefore,considering the previous work on performance evaluation of maize cob thresher,this machine performed satisfactorily and is far better than manual method.The machine is effective,efficient,affordable and available for the small and medium scale farmers in Nigeria.
基金funded by the National Natural Science Foundation of China (No. 51278489)Key Lab for Solid Waste Management and Environmental Safety Open fund (No. 2011-8)
文摘A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge disintegration can destroy the sludge structure and cell wall, so as change the sludge floc structure and moisture distribution, thus affecting the dewatering performance of sludge. In this article, the disintegration methods were ultrasound treatment, K2 Fe O4oxidation and KMn O4 oxidation. The degree of disintegration（DDCOD）, sludge moisture distribution and the final water content of sludge cake after centrifuging were measured. Results showed that three disintegration methods were all effective, and K2 Fe O4oxidation was more efficient than KMn O4 oxidation. The content of free water increased obviously with K2 Fe O4and KMn O4 oxidations, while it decreased with ultrasound treatment. The changes of free water and interstitial water were in the opposite trend. The content of bounding water decreased with K2 Fe O4oxidation, and increased slightly with KMn O4 oxidation, while it increased obviously with ultrasound treatment. The water content of sludge cake after centrifuging decreased with K2 Fe O4oxidation, and did not changed with KMn O4 oxidation, but increased obviously with ultrasound treatment. In summary, ultrasound treatment deteriorated the sludge dewaterability, while K2 Fe O4and KMn O4 oxidation improved the sludge dewaterability.
文摘Steel and rubber are two kinds of materials which are often used for the tracks of off-road vehicles.The objective of this study was to compare tractive performances of steel and rubber grouser shoes under different soil moisture contents.In this study,the tractive performance of single grouser shoe was predicted by soil parameters and three-dimensional shearing model.The soil used in this study was clay soil,and ten different soil moisture contents ranged from 8.58%to 54.36%were applied for investigation of soil parameters.For each soil moisture content,the penetration test,direct shearing test,density and soil moisture content measurement have been performed to obtain the required soil parameters.The experimental results showed that thrust and running resistance of steel single grouser shoe had similar trends to those of rubber single grouser shoe.The thrust of rubber single grouser shoe was always greater than that of steel single grouser shoe with the increase of soil moisture content,and as well as the running resistance.However,the traction of rubber single grouser shoe had a different trend to that of steel single grouser shoe.The traction of steel single grouser shoe was always greater than that of rubber single grouser shoe at any given moisture content except at the stage of less than 15%moisture content.From the experimental results,it can be concluded that the steel single grouser shoe performed better than rubber single grouser shoe in traction for the soil used in this study.
