摘要 :
Coastal soil salinization is an environmental geological problem having obvious impacts on building, environment and agriculture. Evaluating the soil salinization is an urgent issue for the land environment situated with the fast ...
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Coastal soil salinization is an environmental geological problem having obvious impacts on building, environment and agriculture. Evaluating the soil salinization is an urgent issue for the land environment situated with the fast development of civil engineering in southern Laizhou Bay. This paper examines the retrogression of soil quality with samples in 2015. Total salinity and the ions K
+
, Ca
2+
, Na
+
, Mg
2+
, SO
42-
, Cl
-
, CO
3-
, HCO
3-
and pH were detected. The salts in the soils studied are KCl, NaCl, MgCl
2
, CaSO
4
, K
2
SO
4
and Na
2
SO
4
. The spatial analysis of chemical parameters of soils indicates that soil salinity is affected mostly by seawater intrusion and groundwater exploitation. Classification of soils is evaluated by using chemical content and mean salinity with a criterion given by NEA and MOHURD.
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摘要 :
Coastal soil salinization is an environmental geological problem having obvious impacts on building, environment and agriculture. Evaluating the soil salinization is an urgent issue for the land environment situated with the fast ...
展开
Coastal soil salinization is an environmental geological problem having obvious impacts on building, environment and agriculture. Evaluating the soil salinization is an urgent issue for the land environment situated with the fast development of civil engineering in southern Laizhou Bay. This paper examines the retrogression of soil quality with samples in 2015. Total salinity and the ions K
+
, Ca
2+
, Na
+
, Mg
2+
, SO
42-
, Cl
-
, CO
3-
, HCO
3-
and pH were detected. The salts in the soils studied are KCl, NaCl, MgCl
2
, CaSO
4
, K
2
SO
4
and Na
2
SO
4
. The spatial analysis of chemical parameters of soils indicates that soil salinity is affected mostly by seawater intrusion and groundwater exploitation. Classification of soils is evaluated by using chemical content and mean salinity with a criterion given by NEA and MOHURD.
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摘要 :
With graphite, 45 steel and copper as substrates respectively, Ti(C, N)-TiB_2 composite ceramic preforms with micro/nanometric grains were prepared by self-reactive sprayed forming technology. The cooling rate of spray particles d...
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With graphite, 45 steel and copper as substrates respectively, Ti(C, N)-TiB_2 composite ceramic preforms with micro/nanometric grains were prepared by self-reactive sprayed forming technology. The cooling rate of spray particles deposited on different substrates was calculated by finite element method. The influence of cooling rate on morphology of micro/nanometric grains of Ti(C, N)-TiB_2 composite ceramic preforms was studied by means of SEM, XRD and EDS. The results showed that the average cooling rates of particles deposited on the three kinds of substrates were 7.0×10~7℃/s, 8.1×10~7℃/s and 10.7×10~7℃/s respectively. The extremely quick cooling rate was the essential reason why the spray formed preforms were composed of micro/nanometric grains. The TiC_(0.3)N~(0.) grains in preforms deposited on three kinds of substrates all took on anomalous equiaxed grains. Quicker the cooling rates of the deposited particles were, smaller the grains were. The grain size of them was all less than 3μm. Whereas the influence of cooling rate on the morphology of the TiB_2 grains was great. When with graphite as substrate, TiB_2 took on rod-like grains with big length to diameter ratio. When with 45 steel as substrate, it took on near equiaxed grains. And when with copper as substrate, it took on lamina grains with thickness of about 100 nm due to the extremely quick cooling rate and the extremely large degree of supercooling. That's because with the change of the cooling rates, the remaining time of the liquid phases is different, so as to the growing time of the grains along the habit plane is also very different.
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摘要 :
With graphite, 45 steel and copper as substrates respectively, Ti(C, N)-TiB_2 composite ceramic preforms with micro/nanometric grains were prepared by self-reactive sprayed forming technology. The cooling rate of spray particles d...
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With graphite, 45 steel and copper as substrates respectively, Ti(C, N)-TiB_2 composite ceramic preforms with micro/nanometric grains were prepared by self-reactive sprayed forming technology. The cooling rate of spray particles deposited on different substrates was calculated by finite element method. The influence of cooling rate on morphology of micro/nanometric grains of Ti(C, N)-TiB_2 composite ceramic preforms was studied by means of SEM, XRD and EDS. The results showed that the average cooling rates of particles deposited on the three kinds of substrates were 7.0×10~7℃/s, 8.1×10~7℃/s and 10.7×10~7℃/s respectively. The extremely quick cooling rate was the essential reason why the spray formed preforms were composed of micro/nanometric grains. The TiC_(0.3)N~(0.) grains in preforms deposited on three kinds of substrates all took on anomalous equiaxed grains. Quicker the cooling rates of the deposited particles were, smaller the grains were. The grain size of them was all less than 3μm. Whereas the influence of cooling rate on the morphology of the TiB_2 grains was great. When with graphite as substrate, TiB_2 took on rod-like grains with big length to diameter ratio. When with 45 steel as substrate, it took on near equiaxed grains. And when with copper as substrate, it took on lamina grains with thickness of about 100 nm due to the extremely quick cooling rate and the extremely large degree of supercooling. That's because with the change of the cooling rates, the remaining time of the liquid phases is different, so as to the growing time of the grains along the habit plane is also very different.
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摘要 :
The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 μm were compressed and elongat...
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The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 μm were compressed and elongated at quasi-static and high strain rates by a computer controlled servo-hydraulic testing machine and a Split Hopkinson Pressure (Tension) Bar (SHPB and SHTB). The mechanical properties were found to vary significantly with grain size, and strain rate. The relationship between flow stress and grain size can be expressed by a Hall - Petch relation with the different slope for both compressive tests and tensile tests. The influence of strain rate on the slope of the Hall - Petch relation is such that in compression, the slope does not change much, but in tension, there is an increase in the slope value. The strain hardening rate was seen to increase with increasing strain rate. The strain rate dependence of flow stress is obvious, and is seen to be more significant for the smallest grain size specimens. The 3D fractographs illustrated that the numbers of the dimples decrease with the increase of the grain size.
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摘要 :
The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 μm were compressed and elongat...
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The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 μm were compressed and elongated at quasi-static and high strain rates by a computer controlled servo-hydraulic testing machine and a Split Hopkinson Pressure (Tension) Bar (SHPB and SHTB). The mechanical properties were found to vary significantly with grain size, and strain rate. The relationship between flow stress and grain size can be expressed by a Hall - Petch relation with the different slope for both compressive tests and tensile tests. The influence of strain rate on the slope of the Hall - Petch relation is such that in compression, the slope does not change much, but in tension, there is an increase in the slope value. The strain hardening rate was seen to increase with increasing strain rate. The strain rate dependence of flow stress is obvious, and is seen to be more significant for the smallest grain size specimens. The 3D fractographs illustrated that the numbers of the dimples decrease with the increase of the grain size.
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摘要 :
The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 mum were compressed and elongat...
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The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 mum were compressed and elongated at quasi-static and high strain rates by a computer controlled servo-hydraulic testing machine and a Split Hopkinson Pressure (Tension) Bar (SHPB and SHTB). The mechanical properties were found to vary significantly with grain size, and strain rate. The relationship between flow stress and grain size can be expressed by a Hall - Petch relation with the different slope for both compressive tests and tensile tests. The influence of strain rate on the slope of the Hall - Petch relation is such that in compression, the slope does not change much, but in tension, there is an increase in the slope value. The strain hardening rate was seen to increase with increasing strain rate. The strain rate dependence of flow stress is obvious, and is seen to be more significant for the smallest grain size specimens. The 3D fractographs illustrated that the numbers of the dimples decrease with the increase of the grain size.
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摘要 :
Diesel Particulate filter technique is widely recognized as the most effective ways in particulate matter (PM) emission control at present. Different technical routes are applied to filter and regenerate the particles for differen...
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Diesel Particulate filter technique is widely recognized as the most effective ways in particulate matter (PM) emission control at present. Different technical routes are applied to filter and regenerate the particles for different types of diesel engines. Based on the analysis of the characteristics and development status of filter material and regeneration, this thesis studied the matching and integration of filter material and regenerative technology according to the types, common working conditions, fuel qualities and other factors of the diesel engine.
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摘要 :
For the tension distribution problem of cable-driven parallel robot, a new tension distribution method based on normal linear programming is researched. Because cables only sustain tensions, and the limitation of tensions are fini...
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For the tension distribution problem of cable-driven parallel robot, a new tension distribution method based on normal linear programming is researched. Because cables only sustain tensions, and the limitation of tensions are finite, so the computation of cable tensions become very important. By introducing a slack variable and transforming the objective function about tensions into one about slack variable, the optimist tension distribution in feasible zone is obtained. Comparing with the 1-norm optimal algorithm, results show that the optimal tensions received by new method is far away from the boundary of cable tensions, the control of tension distribution is much convenient and the controllable workspace is relatively increased.
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摘要 :
Diesel engine for automobile mainly adopts diesel particulate filter (DPF) method to deal with the exhaust particulate. In order to eliminate the particulate in the filter and complete DPF regeneration, the burner needs to be set ...
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Diesel engine for automobile mainly adopts diesel particulate filter (DPF) method to deal with the exhaust particulate. In order to eliminate the particulate in the filter and complete DPF regeneration, the burner needs to be set at the entrance of DPF. This paper designs the evaporation-type DPF regenerative burner, and makes the bench and the real vehicle test. The test shows that the burner can complete DPF regeneration well within the working scope of the larger engine.
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