The extra-low cyclic fracture problem of medium carbon steel under axial fatigue loading was investigated. Several problems, such as the relations of the cycle times to the depth and tip radius of the notch, loading f...The extra-low cyclic fracture problem of medium carbon steel under axial fatigue loading was investigated. Several problems, such as the relations of the cycle times to the depth and tip radius of the notch, loading frequency, loading range and the parameters of fracture design for medium carbon steel on condition of extra-low axial fatigue loading were discussed based on the experiments. Experimental results indicated that the tension-pressure fatigue loading mode was suitable for extra-low cyclic fatigue fracture design of medium carbon steel and it resulted in low energy consumption, fracture surface with high quality, low cycle times, and high efficiency. The appropriate parameters were as follows： loading frequency 3-5 Hz, notch tip radius r = （0.2-0.3） mm, opening angle α = 60°, and notch depth t = （0.14-0.17）D.展开更多
This paper studies the influence of the inhomogeneous initial stress state in the system consisting of a hollow cylinder and surrounding elastic medium on the dynamics of the moving ring load acting in the interior of...This paper studies the influence of the inhomogeneous initial stress state in the system consisting of a hollow cylinder and surrounding elastic medium on the dynamics of the moving ring load acting in the interior of the cylinder.It is assumed that in the initial state the system is compressed by uniformly distributed normal forces acting at infinity in the radial inward direction and as a result of this compression the inhomogeneous initial stresses appear in the system.After appearance of the initial stresses,the interior of the hollow cylinder is loaded by the moving ring load and so it is required to study the influence of the indicated inhomogeneous initial stresses on the dynamics of this moving load.This influence is studied with utilizing the so-called threedimensional linearized theory of elastic waves in elastic bodies with initial stresses.For solution of the corresponding mathematical problems,the discrete-analytical solution method is employed and the approximate analytical solution of these equations is achieved.Numerical results obtained within this method and related to the influence of the inhomogeneous initial stresses on the critical velocity of the moving load and on the response of the interface stresses to this load are presented and discussed.In particular,it is established that the initial inhomogeneous initial stresses appearing as a result of the action of the aforementioned compressional forces cause to increase the values of the critical velocity of the moving load.展开更多
[Objective] The aim was to research the appropriate seeding quantities of double-season machine-transplanted rice in middle and low-yielding district of southern Jiangxi Province. [Method] The research set five differ...[Objective] The aim was to research the appropriate seeding quantities of double-season machine-transplanted rice in middle and low-yielding district of southern Jiangxi Province. [Method] The research set five different seeding quantities treatments, and compared with conventional seedling treatment, and the appropriate seeding quantities of double season machine-transplanted rice in middle and lowyielding district of southern Jiangxi Province was discussed. [Result] The yields were highest when the seeding quantity was 70 g per tray of early rice by mechanical transplanting and 60 g per tray of late rice. The yield of early rice by mechanical transplanting showed significantly positive correlation with the number of productive ear and the number of seed per ear, and late rice yield showed significant correlation with the number of productive ear by mechanical transplanting. It is key for improving high yields by guaranteeing the number of productive ear. [Conclusion] The issue of proper sowing quantity should be taken into consideration for double-cropping rice in the region, which is crucial for high yields.展开更多
There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to u...There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.展开更多
Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are pre...Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are presented, and show good agreement with the test results. Furthermore, parametric studies are conducted to explore the influence of factors such as the axial compression ratio, shear steel plate ratio, steel ratio, prismatic concrete compression strength, yield strength of angle steel and shear span ratio, etc., on the monotonic load-displacement curves of the ASCCs. Based on a statistical analysis of the calculated results, hysteretic models for load-displacement and moment-curvature are proposed, which agree well with the test results. Finally, some suggestions concerning the conformation of ASCCs are proposed, which could be useful in engineering practice.展开更多
Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated s...Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated spectra are obtained by removing the small cycles of which amplitudes are less than the specified percentages of the maximum amplitude in the basic flight-by-flight loading spectrum and the remainder of the spectrum is untouched. The tests indicate that the mean level of fatigue crack growth life （FCGL） increases as the load truncation level is enhanced. Considering both the time saving and the influence on FCGL, there is an applicable choice （i.e. spectrum S2 or spectrum S3 in this investigation） for full scale fatigue test. The scatter of FCGL becomes much larger than that under the basic spectrum when the load truncation level is increased to a specified high level, mainly due to the occurrence of crack slanting and branching under the high level truncated loading spectra.展开更多
To find the deformation properties of chloride saline soil under the influence of a low temperature environment and different loads,two types of chloride saline soil were selected and their deformation process was tes...To find the deformation properties of chloride saline soil under the influence of a low temperature environment and different loads,two types of chloride saline soil were selected and their deformation process was tested in the laboratory and analyzed during the cooling process in the sensitive cryogenic temperature range.The research results show that high-chloride-salt saline soil underwent little volume change under the no-load condition during the cooling process.Under staticload and dynamic-load conditions,different degrees of settlement deformation occurred;throughout the entire cooling process,another chloride saline soil with a high proportion of sulfate salt underwent volume expansion under no-load and static-load conditions.Under the no-load condition,a certain degree of settlement deformation occurred.Deformation properties were evaluated at different time points during the cooling process for two kinds of chloride saline soil.Finally,deformation characteristics of chloride saline soil were analyzed from the perspective of salt type and crystallization variation under the action of a low-temperature environment and different loads.展开更多
AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning...AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential(120 k Vp) protocol with 350 mg I/m L contrast medium and filtered back projection,and a low tube potential(80 k Vp) protocol with 270 mg I/m L contrast medium with iterative reconstruction.Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor.Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.RESULTS:A 38% reduction in contrast medium dose(360.1 ± 13.3 mg I/kg vs 583.5 ± 21.5 mg I/kg,P < 0.001) and a 73% decrease in radiation dose(1898.5 m Gy·cm vs 6951.8 m Gy·cm) were observed.Interestingly,there was a strong positive correlation in hepatic arterial perfusion(r = 0.907,P < 0.001;r = 0.879,P < 0.001),hepatic portal perfusion(r = 0.819,P = 0.002;r = 0.831,P = 0.002),and hepatic blood flow(r = 0.945,P < 0.001;r = 0.930,P < 0.001) as well as a moderate correlation in hepatic perfusion index(r = 0.736,P = 0.01;r = 0.636,P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor.These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumorto-liver CNR during arterial and portal venous phases(5.63 ± 2.38 vs 6.16 ± 2.60,P = 0.814;4.60 ± 1.27 vs 5.11 ± 1.74,P = 0.587).CONCLUSION:Compared with the conventional protocol,low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.展开更多
Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR activity.Mn-W-Sb modified siderite catalysts were prepared by impregnation meth...Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR activity.Mn-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore,and SCR perfor-mance of the catalysts was investigated.The catalysts were analyzed by X-ray diffrac-tion,H_(2)-temperature-programmed reduction,Brunauer-Emmett-Teller,Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The modified siderite catalysts calcined at 450℃ mainly consist of Fe_(2)O_(3),and added Mn,W and Sb species are amorphous.3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360℃ and good N_(2) selectivity at low temperatures.In-situ DRIFTS results show NH_(4)^(+),coordinated NH_(3),NH_(2),NO_(3)^(-)species(bidentate),NO_(2)-species(nitro,nitro-nitrito,monodentate),and adsorbed NO_(2) can be discovered on the sur-face of Mn-W-Sb modified siderite catalysts,and doping of Mn will enhance adsorbed NO_(2) formation by synergistic catalysis with Fe^(3+).In addition,the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO_(2) and H_(2)O.Time-dependent in-situ DRIFTS studies also indicate that both of Lewis and Br?nsted acid sites play a role in SCR of NO by ammonia at low temperatures.The mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction pathways.The mechanism of NO,oxidized by synergistic catalysis of Fe^(3+)and Mn^(4+/3+)to form NO_(2) among three pathways,reveals the reason of high NO_(x) conversion of the catalyst at medium and low temperatures.展开更多
Development of the medium and low voltage DC distribution system is of great significance to a regional transmission of electric energy,increasing a penetration rate of new energy,and enhancing a safety of the operati...Development of the medium and low voltage DC distribution system is of great significance to a regional transmission of electric energy,increasing a penetration rate of new energy,and enhancing a safety of the operation of the AC/DC interconnected grid.This paper first summarizes the medium and low voltage DC distribution system schemes and plans put forward by many countries,and then elaborate status of under-construction medium and low voltage DC distribution system project cases in China.Based on these project cases,this paper analyzes key issues involved in the medium and low voltage DC distribution system topologies,equipment,operation control technologies and DC fault protections,in order to provide theoretical and technical reference for future medium and low voltage DC distribution system-related projects.Finally,this paper combines a current China research status to summarize and give a prediction about the future research direction of medium and low voltage DC distribution system,which can provide reference for the research of medium and low voltage DC distribution system.展开更多
In order to study the effect of time lag and stress loading rates on rock deformation,the conventional stepped stress loading mode was changed into a continuous mode to investigate the effect of effective pressure on ...In order to study the effect of time lag and stress loading rates on rock deformation,the conventional stepped stress loading mode was changed into a continuous mode to investigate the effect of effective pressure on permeability and porosity.The time lag effect of rock deformation illustrating the relationship between changes in permeability and steady time was studied.Permeability reduction ratios were measured under different stress loading rates which were achieved by different pump rate settings.The results show that permeability and porosity gradually decrease with increases in effective pressure.Permeability at high effective pressure attains stability quickly.Steady times at low effective pressure are very long.Reduction in permeability at lower stress loading rates is small,while,in contrast,it is large at high stress loading rates.展开更多
The introduction of surface engineering is expected to be an effective strategy against fretting damage.A large number of studies show that the low gas multi-component(such as carbon,nitrogen,sulphur and oxygen,etc)th...The introduction of surface engineering is expected to be an effective strategy against fretting damage.A large number of studies show that the low gas multi-component(such as carbon,nitrogen,sulphur and oxygen,etc)thermo-chemical treatment(LTGMTT)can overcome the brittleness of nitriding process,and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly.However,there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now,which limits the applications of fretting.So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50(0.48%C)steel prepared by low temperature gas multi-component thermo-chemical treatment(LTGMTT)technology.The fretting wear tests of the modified layer flat specimens and its substrate(LZ50 steel)against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2μm to 40μm.Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope(SEM),optical microscope(OM),X-ray diffraction(XRD)and surface profilometer.The experimental results showed that the modified layer with a total thickness of 60μm was consisted of three parts,i.e.,loose layer,compound layer and diffusion layer.Compared with the substrate,the range of the mixed fretting regime(MFR)of the LTGMTT modified layer diminished,and the slip regime(SR)of the modified layer shifted to the direction of smaller displacement amplitude.The coefficient of friction(COF)of the modified layer was lower than that of the substrate in the initial stage.For the modified layer,the damage in partial slip regime(PSR)was very slight.The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination.The modified layer presented better wear resistance than the substrate in PSR and MFR;however,in SR,the wear resistance of the modified layer decreased with the increase of the displacement amplitudes.The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.展开更多
AIM:To assess the efficacy and advantages of 4-wk pegylated interferon a-2a(peg-IFN-a2a) monotherapy for chronic hepatitis C patients with strong predictors of sustained virologic response(SVR).METHODS:Patients(n = 33...AIM:To assess the efficacy and advantages of 4-wk pegylated interferon a-2a(peg-IFN-a2a) monotherapy for chronic hepatitis C patients with strong predictors of sustained virologic response(SVR).METHODS:Patients(n = 33) with genotype 2 and low viral load(< 100 KIU/mL),who became HCV RNA negative after 1 wk of IFN treatment,were randomly allocated to receive a 4-or 12-wk treatment course at a ratio of 2:1,respectively,with a subsequent 24-wk follow-up period.Peg-IFN-a2a was administered subcutaneously at a dose of 180 μg or 90 μg once weekly.SVR was defined as absence of serum HCV RNA at the end of the follow-up period.RESULTS:All patients completed the treatment schedule,and more than half were symptom-free during the treatment.In the 4-wk treatment group,20 of 22(91%) patients achieved SVR.Two patients relapsed,but achieved SVR following re-treatment with peg-IFN-a2a alone.In the 12-wk treatment group,11 of 11(100%) patients attained SVR.CONCLUSION:Our results show that a 4-wk course of peg-IFN-a2a monotherapy can achieve a high SVR rate in "IFN-sensitive" patients,without negatively affecting outcome.展开更多
This paper presents an analytical layer-element method used to analyze the displacement of a multi-layered transversely isotropic elastic medium of arbitrary depth subjected to axisymmetric loading.Based on the basic ...This paper presents an analytical layer-element method used to analyze the displacement of a multi-layered transversely isotropic elastic medium of arbitrary depth subjected to axisymmetric loading.Based on the basic constitutive equations and the HU Hai-chang's solutions for transversely isotropic elastic media,the state vectors of a multi-layered transversely isotropic medium were deduced.From the state vectors,an analytical layer element for a single layer(i.e.,a symmetric and exact stiffness matrix) was acquired in the Hankel transformed domain,which not only simplified the calculation but also improved the numerical efficiency and stability due to the absence of positive exponential functions.The global stiffness matrix was obtained by assembling the interrelated layer elements based on the principle of the finite layer method.By solving the algebraic equations of the global stiffness matrix which satisfy the boundary conditions,the solutions for multi-layered transversely isotropic media in the Hankel transformed domain were obtained.The actual solutions of this problem in the physical domain were acquired by inverting the Hankel transform.This paper presents numerical examples to verify the proposed solutions and investigate the influence of the properties of the multi-layered medium on the load-displacement response.展开更多
The influence of soaking time in deep cryogenic treatment on the tensile and impact properties of low-alloy medium-carbon HY-TUF steel was investigated in this study. Microstructural studies based on phase distributio...The influence of soaking time in deep cryogenic treatment on the tensile and impact properties of low-alloy medium-carbon HY-TUF steel was investigated in this study. Microstructural studies based on phase distribution mapping by electron backscatter diffraction show that the deep cryogenic process causes a decrease in the content of retained austenite and an increase in the volume fraction of η-carbide with increasing soaking time up to 48 h. The decrease in the content of retained austenite from ~1.23vol% to 0.48vol% suggests an isothermal martensitic transformation at 77 K. The η-type precipitates formed in deep cryogenic-treated martensite over 48 h have the Hirotsu and Nagakura orientation relation with the martensitic matrix. Furthermore, a high coherency between η-carbide and the martensitic matrix is observed by high-resolution transmission electron microscopy. The variations in macrohardness, yield strength, ultimate tensile strength, and ductility with soaking time in the deep cryogenic process show a peak/plateau trend.展开更多
Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading o...Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance,which could cause such problems as battery weight gain,mass transport blocking,and catalyst loss.We report herein the preparation of fine CoNi nanoparticles(5-6 nm)anchored inside a nitrogendoped defective carbon nanotube network(CoNi@N-DCNT)by a transient Joule heating method.When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media,the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm^(-2) showed excellent bifunctional catalytic performance.For ORR,the onset potential(Eonset)and the half-wave potential(E_(1/2))were 0.92 V versus reversible hydrogen electrode(vs.RHE)and 0.83 V(vs.RHE),respectively.For OER,the potential at the current density(J)of 10 mA cm^(-2)(E_(10))was 1.53 V,resulting in an overpotential of 300 mV much lower than that of the commercial RuO_(2) catalyst(320 mV).The potential gap between E_(1/2) and E_(10) was as small as 0.7 V.Considering the low mass loading,the mass activity at E_(10) reached at 123.2 A g^(-1),much larger than that of the RuO_(2) catalyst and literature results of transitional metal-based bifunctional catalysts.Moreover,the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test.The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.展开更多
A CMOS active mixer based on voltage control load technique which can operate at 1.0 V supply voltage was proposed, and its operation principle, noise and linearity analysis were also presented. Contrary to the conven...A CMOS active mixer based on voltage control load technique which can operate at 1.0 V supply voltage was proposed, and its operation principle, noise and linearity analysis were also presented. Contrary to the conventional Gilbert-type mixer which is based on RF current-commutating, the load impedance in this proposed mixer is controlled by the LO signal, and it has only two stacked transistors at each branch which is suitable for low voltage applications. The mixer was designed and fabricated in 0.18 tam CMOS process for 2.4 GHz ISM band applications. With an input of 2.44 GHz RF signal and 2.442 GHz LO signal, the measurement specifications of the proposed mixer are： the conversion gain （Gc） is 5.3 dB, the input-referred third-order intercept point （PIIP3） is 4.6 dBm, the input-referred 1 dB compression point （P1dB） is --7.4 dBm, and the single-sideband noise figure （NFSSB） is 21.7 dB.展开更多
Objective To evaluate the feasibility of using a low concentration of contrast medium （Visipaque 270 mgl/mL）, low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography ang...Objective To evaluate the feasibility of using a low concentration of contrast medium （Visipaque 270 mgl/mL）, low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography angiography （CTA）. Methods Forty patients （22 men and 18 women; average age 48.7 ± 14.25 years; average body mass index 23.9 ± 3.7 kg/m^2） undergoing CTA for suspected vascular diseases were randomly assigned into two groups. Group A （n = 20） was administered 370 mgl/mL contrast medium, and group B （n = 20） was administered 270 mgl/mL contrast medium. Both groups were administered at a rate of 4.8 mL/s and an injection volume of 0.8 mL/kg. Images of group A were obtained with 120 kVp and filtered back projection （FBP） reconstruction, whereas images of group B were obtained with 80 kVp and 80% adaptive iterative statistical reconstruction algorithm （ASiR）. The CT values and standard deviations of intracranial arteries and image noise on the corona radiata were measured to calculate the contrast-to-noise ratio （CNR） and signal-to-noise ratio （SNR）. The beam-hardening artifacts （BHAs） around the skull base were calculated. Two readers evaluated the image quality with volume rendered images using scores from 1 to 5. The values between the two groups were statistically compared. Results The mean CT value of the intracranial arteries in group B was significantly higher than that in group A （P 〈 0.001）. The CNR and SNR values in group B were also statistically higher than those in group A （P 〈 0.001）. Image noise and BHAs were not significantly different between the two groups. The image quality score of VR images of in group B was significantly higher than that in group A （P = 0.001）. However, the quality scores of axial enhancement images in group B became significantly smaller than those in group A （P〈 0.001）. The CT dose index volume and dose-length product were decreased by 63.8% and 64%, respectively, in group B （P 〈 0.001 for both）. Conclusion Visipaque combined with 80 kVp and 80% ASiR provided similar image quality in intracranial CTA with 64% radiation dose reduction compared with the use of lopamidol, 120 kVp, and FBP reconstruc-tion.展开更多
The main concern of this paper is to provide an extensive study for the structural behavior of low/medium/high rise office buildings aiming to deepen structure and architect designers understanding for such type of bu...The main concern of this paper is to provide an extensive study for the structural behavior of low/medium/high rise office buildings aiming to deepen structure and architect designers understanding for such type of buildings. The study is performed on reinforced concrete and emphasized only on Kuwait city conditions for wind. Regular layout plan building with different heights ranging from five to fifty typical office stories are investigated in this study. Three dimensional finite element techniques through ETABS software are used in conducting analysis for structures presented here-in. A serviceability study is performed to ensure that buildings have sufficient stability to limit lateral drift and peak acceleration within the acceptable range of occupancy comfort. In addition, an ultimate strength study is carried out to design and verify that all the structural elements are designed to withstand factored gravity and lateral loadings in a safe manner according to the international building codes. The building slenderness ratio and the building core size and location are the studied parameters since they are the key drivers for the efficient structural design. Analysis results are presented and discussed and finally conclusions are summarized as guidelines for designers of concrete office buildings in Kuwait.展开更多
With the increasing application of anammox for the treatment of high-strength industrial wastewater,application of anammox in municipal sewage has been gaining more attention.Sludge granulation in particular enhances ...With the increasing application of anammox for the treatment of high-strength industrial wastewater,application of anammox in municipal sewage has been gaining more attention.Sludge granulation in particular enhances the enrichment and retention of anammox bacteria in municipal sewage treatment systems.However,the performance of granular sludge under continuous and varying hydraulic loading shock remains little understood.In this study,the robustness of anammox granular sludge in treating lowstrength municipal sewage under various shock loadings was investigated.Results showed that an upflow anaerobic sludge blanket(UASB)reactor with anammox granules performed well,with anammox specific activity up to 0.28 kg N/kg VSS/day and anti-loading shock capability up to 187.2 L/day during the 8-month testing period.The accumulation rate of N2O(<0.01 kg N/kg VSS/day)in the liquid phase was seven times higher than that of the gas phase,which could be mainly attributed to the incomplete denitrification and insufficient carbon source.However,only a small part of the produced N2O escaped into the atmosphere.High-throughput sequencing and molecular ecological network analyses also identified the bacterial diversity and community structure,indicating the potential resistance against loading shock.The composition and structural analyses showed that polysaccharides were an important functional component in the tightly bound extracellular polymeric substances(TB-EPS),which was the major EPS layer of anammox granules.Scanning electron microscopy(SEM)also showed that the gaps in between the anammoxclusters in the granules inhibit the flotation of the sludge and ensure efficient settling and retention of anammox granules.展开更多
基金supported by the Ministry of Education of China(No.208152)Gansu Natural Science Foundation(No.3ZS061-A52-47).
文摘The extra-low cyclic fracture problem of medium carbon steel under axial fatigue loading was investigated. Several problems, such as the relations of the cycle times to the depth and tip radius of the notch, loading frequency, loading range and the parameters of fracture design for medium carbon steel on condition of extra-low axial fatigue loading were discussed based on the experiments. Experimental results indicated that the tension-pressure fatigue loading mode was suitable for extra-low cyclic fatigue fracture design of medium carbon steel and it resulted in low energy consumption, fracture surface with high quality, low cycle times, and high efficiency. The appropriate parameters were as follows： loading frequency 3-5 Hz, notch tip radius r = （0.2-0.3） mm, opening angle α = 60°, and notch depth t = （0.14-0.17）D.
文摘This paper studies the influence of the inhomogeneous initial stress state in the system consisting of a hollow cylinder and surrounding elastic medium on the dynamics of the moving ring load acting in the interior of the cylinder.It is assumed that in the initial state the system is compressed by uniformly distributed normal forces acting at infinity in the radial inward direction and as a result of this compression the inhomogeneous initial stresses appear in the system.After appearance of the initial stresses,the interior of the hollow cylinder is loaded by the moving ring load and so it is required to study the influence of the indicated inhomogeneous initial stresses on the dynamics of this moving load.This influence is studied with utilizing the so-called threedimensional linearized theory of elastic waves in elastic bodies with initial stresses.For solution of the corresponding mathematical problems,the discrete-analytical solution method is employed and the approximate analytical solution of these equations is achieved.Numerical results obtained within this method and related to the influence of the inhomogeneous initial stresses on the critical velocity of the moving load and on the response of the interface stresses to this load are presented and discussed.In particular,it is established that the initial inhomogeneous initial stresses appearing as a result of the action of the aforementioned compressional forces cause to increase the values of the critical velocity of the moving load.
基金National Key Technology R&D Program of the Ministry of Science and Technology(2011BAD16B04,(2012BAD04B11)~~
文摘[Objective] The aim was to research the appropriate seeding quantities of double-season machine-transplanted rice in middle and low-yielding district of southern Jiangxi Province. [Method] The research set five different seeding quantities treatments, and compared with conventional seedling treatment, and the appropriate seeding quantities of double season machine-transplanted rice in middle and lowyielding district of southern Jiangxi Province was discussed. [Result] The yields were highest when the seeding quantity was 70 g per tray of early rice by mechanical transplanting and 60 g per tray of late rice. The yield of early rice by mechanical transplanting showed significantly positive correlation with the number of productive ear and the number of seed per ear, and late rice yield showed significant correlation with the number of productive ear by mechanical transplanting. It is key for improving high yields by guaranteeing the number of productive ear. [Conclusion] The issue of proper sowing quantity should be taken into consideration for double-cropping rice in the region, which is crucial for high yields.
基金supported by National Natural Science Foundation of China (Grant No. 50875173)Shanghai Municipal Education Commission Key Foundation of China (Grant No. 09ZZ157)Shanghai Leading Academic Discipline Project of China (Grant No. J50503)
文摘There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.
基金the New Century Excellent Talents in University Under Grant No.290Heilongjiang Key Program on Science and Technology Under Grant No. GC04A609arbin Key Program on Science and Technology Under Grant No. 2004AA9CS187.
文摘Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are presented, and show good agreement with the test results. Furthermore, parametric studies are conducted to explore the influence of factors such as the axial compression ratio, shear steel plate ratio, steel ratio, prismatic concrete compression strength, yield strength of angle steel and shear span ratio, etc., on the monotonic load-displacement curves of the ASCCs. Based on a statistical analysis of the calculated results, hysteretic models for load-displacement and moment-curvature are proposed, which agree well with the test results. Finally, some suggestions concerning the conformation of ASCCs are proposed, which could be useful in engineering practice.
基金National Natural Science Foundation of China (10802003)
文摘Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated spectra are obtained by removing the small cycles of which amplitudes are less than the specified percentages of the maximum amplitude in the basic flight-by-flight loading spectrum and the remainder of the spectrum is untouched. The tests indicate that the mean level of fatigue crack growth life （FCGL） increases as the load truncation level is enhanced. Considering both the time saving and the influence on FCGL, there is an applicable choice （i.e. spectrum S2 or spectrum S3 in this investigation） for full scale fatigue test. The scatter of FCGL becomes much larger than that under the basic spectrum when the load truncation level is increased to a specified high level, mainly due to the occurrence of crack slanting and branching under the high level truncated loading spectra.
基金supported by National Natural Science Foundation of China (No. 41501062)
文摘To find the deformation properties of chloride saline soil under the influence of a low temperature environment and different loads,two types of chloride saline soil were selected and their deformation process was tested in the laboratory and analyzed during the cooling process in the sensitive cryogenic temperature range.The research results show that high-chloride-salt saline soil underwent little volume change under the no-load condition during the cooling process.Under staticload and dynamic-load conditions,different degrees of settlement deformation occurred;throughout the entire cooling process,another chloride saline soil with a high proportion of sulfate salt underwent volume expansion under no-load and static-load conditions.Under the no-load condition,a certain degree of settlement deformation occurred.Deformation properties were evaluated at different time points during the cooling process for two kinds of chloride saline soil.Finally,deformation characteristics of chloride saline soil were analyzed from the perspective of salt type and crystallization variation under the action of a low-temperature environment and different loads.
基金National Natural Science Foundation of China,No.NSFC 81171389Key Program of Basic Research from Shanghai Municipal Science and Technology Commission,No.12JC1406500the Program of Shanghai Municipal Health Outstanding Discipline Leader,No.XBR 2013110
文摘AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential(120 k Vp) protocol with 350 mg I/m L contrast medium and filtered back projection,and a low tube potential(80 k Vp) protocol with 270 mg I/m L contrast medium with iterative reconstruction.Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor.Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.RESULTS:A 38% reduction in contrast medium dose(360.1 ± 13.3 mg I/kg vs 583.5 ± 21.5 mg I/kg,P < 0.001) and a 73% decrease in radiation dose(1898.5 m Gy·cm vs 6951.8 m Gy·cm) were observed.Interestingly,there was a strong positive correlation in hepatic arterial perfusion(r = 0.907,P < 0.001;r = 0.879,P < 0.001),hepatic portal perfusion(r = 0.819,P = 0.002;r = 0.831,P = 0.002),and hepatic blood flow(r = 0.945,P < 0.001;r = 0.930,P < 0.001) as well as a moderate correlation in hepatic perfusion index(r = 0.736,P = 0.01;r = 0.636,P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor.These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumorto-liver CNR during arterial and portal venous phases(5.63 ± 2.38 vs 6.16 ± 2.60,P = 0.814;4.60 ± 1.27 vs 5.11 ± 1.74,P = 0.587).CONCLUSION:Compared with the conventional protocol,low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.
基金This work was supported by the National Natural Science Foundation of China(Nos.51406077 and 51276039).
文摘Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR activity.Mn-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore,and SCR perfor-mance of the catalysts was investigated.The catalysts were analyzed by X-ray diffrac-tion,H_(2)-temperature-programmed reduction,Brunauer-Emmett-Teller,Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The modified siderite catalysts calcined at 450℃ mainly consist of Fe_(2)O_(3),and added Mn,W and Sb species are amorphous.3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360℃ and good N_(2) selectivity at low temperatures.In-situ DRIFTS results show NH_(4)^(+),coordinated NH_(3),NH_(2),NO_(3)^(-)species(bidentate),NO_(2)-species(nitro,nitro-nitrito,monodentate),and adsorbed NO_(2) can be discovered on the sur-face of Mn-W-Sb modified siderite catalysts,and doping of Mn will enhance adsorbed NO_(2) formation by synergistic catalysis with Fe^(3+).In addition,the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO_(2) and H_(2)O.Time-dependent in-situ DRIFTS studies also indicate that both of Lewis and Br?nsted acid sites play a role in SCR of NO by ammonia at low temperatures.The mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction pathways.The mechanism of NO,oxidized by synergistic catalysis of Fe^(3+)and Mn^(4+/3+)to form NO_(2) among three pathways,reveals the reason of high NO_(x) conversion of the catalyst at medium and low temperatures.
基金supported by the National Key Rese arch and Development Program of China(2018YFB0904100)Science and Technology Project of State Grid(SGHB0000KXJS1800685)
文摘Development of the medium and low voltage DC distribution system is of great significance to a regional transmission of electric energy,increasing a penetration rate of new energy,and enhancing a safety of the operation of the AC/DC interconnected grid.This paper first summarizes the medium and low voltage DC distribution system schemes and plans put forward by many countries,and then elaborate status of under-construction medium and low voltage DC distribution system project cases in China.Based on these project cases,this paper analyzes key issues involved in the medium and low voltage DC distribution system topologies,equipment,operation control technologies and DC fault protections,in order to provide theoretical and technical reference for future medium and low voltage DC distribution system-related projects.Finally,this paper combines a current China research status to summarize and give a prediction about the future research direction of medium and low voltage DC distribution system,which can provide reference for the research of medium and low voltage DC distribution system.
基金Projects 2008ZX05009-004 supported by the National Key Sci-Tech Major Special Item2006CB705805 by the National Basic Research Program of Chinasupported by the National Basic Research Program of China and "enhanced oil recovery basic theory for low permeability reservoirs" under grant 2002CCA00700
文摘In order to study the effect of time lag and stress loading rates on rock deformation,the conventional stepped stress loading mode was changed into a continuous mode to investigate the effect of effective pressure on permeability and porosity.The time lag effect of rock deformation illustrating the relationship between changes in permeability and steady time was studied.Permeability reduction ratios were measured under different stress loading rates which were achieved by different pump rate settings.The results show that permeability and porosity gradually decrease with increases in effective pressure.Permeability at high effective pressure attains stability quickly.Steady times at low effective pressure are very long.Reduction in permeability at lower stress loading rates is small,while,in contrast,it is large at high stress loading rates.
基金supported by National Natural Science Foundation of China(Grant No.50521503)National Basic Research Program of China(973 Program,Grant No.2007CB714704)National Hi-tech Research and Development Program of China(863 Program,Grant No.2006AA04Z406)
文摘The introduction of surface engineering is expected to be an effective strategy against fretting damage.A large number of studies show that the low gas multi-component(such as carbon,nitrogen,sulphur and oxygen,etc)thermo-chemical treatment(LTGMTT)can overcome the brittleness of nitriding process,and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly.However,there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now,which limits the applications of fretting.So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50(0.48%C)steel prepared by low temperature gas multi-component thermo-chemical treatment(LTGMTT)technology.The fretting wear tests of the modified layer flat specimens and its substrate(LZ50 steel)against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2μm to 40μm.Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope(SEM),optical microscope(OM),X-ray diffraction(XRD)and surface profilometer.The experimental results showed that the modified layer with a total thickness of 60μm was consisted of three parts,i.e.,loose layer,compound layer and diffusion layer.Compared with the substrate,the range of the mixed fretting regime(MFR)of the LTGMTT modified layer diminished,and the slip regime(SR)of the modified layer shifted to the direction of smaller displacement amplitude.The coefficient of friction(COF)of the modified layer was lower than that of the substrate in the initial stage.For the modified layer,the damage in partial slip regime(PSR)was very slight.The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination.The modified layer presented better wear resistance than the substrate in PSR and MFR;however,in SR,the wear resistance of the modified layer decreased with the increase of the displacement amplitudes.The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.
基金Supported by Clinical Research Funds from Department of Gastroenterology and Hepatology,Kashiwa Hospital,Jikei University School of Medicine
文摘AIM:To assess the efficacy and advantages of 4-wk pegylated interferon a-2a(peg-IFN-a2a) monotherapy for chronic hepatitis C patients with strong predictors of sustained virologic response(SVR).METHODS:Patients(n = 33) with genotype 2 and low viral load(< 100 KIU/mL),who became HCV RNA negative after 1 wk of IFN treatment,were randomly allocated to receive a 4-or 12-wk treatment course at a ratio of 2:1,respectively,with a subsequent 24-wk follow-up period.Peg-IFN-a2a was administered subcutaneously at a dose of 180 μg or 90 μg once weekly.SVR was defined as absence of serum HCV RNA at the end of the follow-up period.RESULTS:All patients completed the treatment schedule,and more than half were symptom-free during the treatment.In the 4-wk treatment group,20 of 22(91%) patients achieved SVR.Two patients relapsed,but achieved SVR following re-treatment with peg-IFN-a2a alone.In the 12-wk treatment group,11 of 11(100%) patients attained SVR.CONCLUSION:Our results show that a 4-wk course of peg-IFN-a2a monotherapy can achieve a high SVR rate in "IFN-sensitive" patients,without negatively affecting outcome.
基金Project (No.50578121) supported by the National Natural Science Foundation of China
文摘This paper presents an analytical layer-element method used to analyze the displacement of a multi-layered transversely isotropic elastic medium of arbitrary depth subjected to axisymmetric loading.Based on the basic constitutive equations and the HU Hai-chang's solutions for transversely isotropic elastic media,the state vectors of a multi-layered transversely isotropic medium were deduced.From the state vectors,an analytical layer element for a single layer(i.e.,a symmetric and exact stiffness matrix) was acquired in the Hankel transformed domain,which not only simplified the calculation but also improved the numerical efficiency and stability due to the absence of positive exponential functions.The global stiffness matrix was obtained by assembling the interrelated layer elements based on the principle of the finite layer method.By solving the algebraic equations of the global stiffness matrix which satisfy the boundary conditions,the solutions for multi-layered transversely isotropic media in the Hankel transformed domain were obtained.The actual solutions of this problem in the physical domain were acquired by inverting the Hankel transform.This paper presents numerical examples to verify the proposed solutions and investigate the influence of the properties of the multi-layered medium on the load-displacement response.
文摘The influence of soaking time in deep cryogenic treatment on the tensile and impact properties of low-alloy medium-carbon HY-TUF steel was investigated in this study. Microstructural studies based on phase distribution mapping by electron backscatter diffraction show that the deep cryogenic process causes a decrease in the content of retained austenite and an increase in the volume fraction of η-carbide with increasing soaking time up to 48 h. The decrease in the content of retained austenite from ~1.23vol% to 0.48vol% suggests an isothermal martensitic transformation at 77 K. The η-type precipitates formed in deep cryogenic-treated martensite over 48 h have the Hirotsu and Nagakura orientation relation with the martensitic matrix. Furthermore, a high coherency between η-carbide and the martensitic matrix is observed by high-resolution transmission electron microscopy. The variations in macrohardness, yield strength, ultimate tensile strength, and ductility with soaking time in the deep cryogenic process show a peak/plateau trend.
基金the financial supports from the National Natural Science Foundation of China(21975281,21773293,21603264)CAS Pioneer Hundred Talents Program+2 种基金the National Key Research and Development Program of China(2016YFA0203301)Jiangsu Planned Projects for Postdoctoral Research Funds(2019K048)Suzhou Science and Technology Plan Project(SYG201926)。
文摘Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance,which could cause such problems as battery weight gain,mass transport blocking,and catalyst loss.We report herein the preparation of fine CoNi nanoparticles(5-6 nm)anchored inside a nitrogendoped defective carbon nanotube network(CoNi@N-DCNT)by a transient Joule heating method.When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media,the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm^(-2) showed excellent bifunctional catalytic performance.For ORR,the onset potential(Eonset)and the half-wave potential(E_(1/2))were 0.92 V versus reversible hydrogen electrode(vs.RHE)and 0.83 V(vs.RHE),respectively.For OER,the potential at the current density(J)of 10 mA cm^(-2)(E_(10))was 1.53 V,resulting in an overpotential of 300 mV much lower than that of the commercial RuO_(2) catalyst(320 mV).The potential gap between E_(1/2) and E_(10) was as small as 0.7 V.Considering the low mass loading,the mass activity at E_(10) reached at 123.2 A g^(-1),much larger than that of the RuO_(2) catalyst and literature results of transitional metal-based bifunctional catalysts.Moreover,the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test.The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.
基金Project(61166004) supported by the National Natural Science Foundation of ChinaProject(09ZCGHHZ00200) supported by the International Scientific and Technological Cooperation Program of Science and Technology Plan of Tianjin,ChinaProject(UF10028Y)supported by the Doctoral Scientific Research Foundation for Guilin University of Electronic Technology,China
文摘A CMOS active mixer based on voltage control load technique which can operate at 1.0 V supply voltage was proposed, and its operation principle, noise and linearity analysis were also presented. Contrary to the conventional Gilbert-type mixer which is based on RF current-commutating, the load impedance in this proposed mixer is controlled by the LO signal, and it has only two stacked transistors at each branch which is suitable for low voltage applications. The mixer was designed and fabricated in 0.18 tam CMOS process for 2.4 GHz ISM band applications. With an input of 2.44 GHz RF signal and 2.442 GHz LO signal, the measurement specifications of the proposed mixer are： the conversion gain （Gc） is 5.3 dB, the input-referred third-order intercept point （PIIP3） is 4.6 dBm, the input-referred 1 dB compression point （P1dB） is --7.4 dBm, and the single-sideband noise figure （NFSSB） is 21.7 dB.
文摘Objective To evaluate the feasibility of using a low concentration of contrast medium （Visipaque 270 mgl/mL）, low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography angiography （CTA）. Methods Forty patients （22 men and 18 women; average age 48.7 ± 14.25 years; average body mass index 23.9 ± 3.7 kg/m^2） undergoing CTA for suspected vascular diseases were randomly assigned into two groups. Group A （n = 20） was administered 370 mgl/mL contrast medium, and group B （n = 20） was administered 270 mgl/mL contrast medium. Both groups were administered at a rate of 4.8 mL/s and an injection volume of 0.8 mL/kg. Images of group A were obtained with 120 kVp and filtered back projection （FBP） reconstruction, whereas images of group B were obtained with 80 kVp and 80% adaptive iterative statistical reconstruction algorithm （ASiR）. The CT values and standard deviations of intracranial arteries and image noise on the corona radiata were measured to calculate the contrast-to-noise ratio （CNR） and signal-to-noise ratio （SNR）. The beam-hardening artifacts （BHAs） around the skull base were calculated. Two readers evaluated the image quality with volume rendered images using scores from 1 to 5. The values between the two groups were statistically compared. Results The mean CT value of the intracranial arteries in group B was significantly higher than that in group A （P 〈 0.001）. The CNR and SNR values in group B were also statistically higher than those in group A （P 〈 0.001）. Image noise and BHAs were not significantly different between the two groups. The image quality score of VR images of in group B was significantly higher than that in group A （P = 0.001）. However, the quality scores of axial enhancement images in group B became significantly smaller than those in group A （P〈 0.001）. The CT dose index volume and dose-length product were decreased by 63.8% and 64%, respectively, in group B （P 〈 0.001 for both）. Conclusion Visipaque combined with 80 kVp and 80% ASiR provided similar image quality in intracranial CTA with 64% radiation dose reduction compared with the use of lopamidol, 120 kVp, and FBP reconstruc-tion.
文摘The main concern of this paper is to provide an extensive study for the structural behavior of low/medium/high rise office buildings aiming to deepen structure and architect designers understanding for such type of buildings. The study is performed on reinforced concrete and emphasized only on Kuwait city conditions for wind. Regular layout plan building with different heights ranging from five to fifty typical office stories are investigated in this study. Three dimensional finite element techniques through ETABS software are used in conducting analysis for structures presented here-in. A serviceability study is performed to ensure that buildings have sufficient stability to limit lateral drift and peak acceleration within the acceptable range of occupancy comfort. In addition, an ultimate strength study is carried out to design and verify that all the structural elements are designed to withstand factored gravity and lateral loadings in a safe manner according to the international building codes. The building slenderness ratio and the building core size and location are the studied parameters since they are the key drivers for the efficient structural design. Analysis results are presented and discussed and finally conclusions are summarized as guidelines for designers of concrete office buildings in Kuwait.
基金financially supported by the National Natural Science Foundation of China (Nos. 21707155, 41671471, 41322012 and 91851204)the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB15020303)+4 种基金the National Key R&D Program (No. 2016YFA0602303)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01Z176)the special fund from the State Key Joint Laboratory of Environment Simulation and Pollution Control (Research Center for Eco-environmental Sciences, Chinese Academy of Sciences) (No. 18Z02ESPCR)the support of a Humboldt Research Fellowship (No. 1152633)Program of the Youth Innovation Promotion Association (CAS)
文摘With the increasing application of anammox for the treatment of high-strength industrial wastewater,application of anammox in municipal sewage has been gaining more attention.Sludge granulation in particular enhances the enrichment and retention of anammox bacteria in municipal sewage treatment systems.However,the performance of granular sludge under continuous and varying hydraulic loading shock remains little understood.In this study,the robustness of anammox granular sludge in treating lowstrength municipal sewage under various shock loadings was investigated.Results showed that an upflow anaerobic sludge blanket(UASB)reactor with anammox granules performed well,with anammox specific activity up to 0.28 kg N/kg VSS/day and anti-loading shock capability up to 187.2 L/day during the 8-month testing period.The accumulation rate of N2O(<0.01 kg N/kg VSS/day)in the liquid phase was seven times higher than that of the gas phase,which could be mainly attributed to the incomplete denitrification and insufficient carbon source.However,only a small part of the produced N2O escaped into the atmosphere.High-throughput sequencing and molecular ecological network analyses also identified the bacterial diversity and community structure,indicating the potential resistance against loading shock.The composition and structural analyses showed that polysaccharides were an important functional component in the tightly bound extracellular polymeric substances(TB-EPS),which was the major EPS layer of anammox granules.Scanning electron microscopy(SEM)also showed that the gaps in between the anammoxclusters in the granules inhibit the flotation of the sludge and ensure efficient settling and retention of anammox granules.
