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High velocity impact of metal sphere on thin metallic plate using smooth particle hydrodynamics (SPH)

Hossein ASADI KALAMEH, Arash KARAMALI, Cosmin ANITESCU, Timon RABCZUK

《结构与土木工程前沿（英文）》 2012年 第6卷 第2期   页码 101-110 doi: 10.1007/s11709-012-0160-z

摘要： The modeling of high velocity impact is an important topic in impact engineering. Due to various constraints, experimental data are extremely limited. Therefore, detailed numerical simulation can be considered as a desirable alternative. However, the physical processes involved in the impact are very sophisticated; hence a practical and complete reproduction of the phenomena involves complicated numerical models. In this paper, we present a smoothed particle hydrodynamics (SPH) method to model two-dimensional impact of metal sphere on thin metallic plate. The simulations are applied to different materials (Aluminum, Lead and Steel); however the target and projectile are formed of similar metals. A wide range of velocities (300, 1000, 2000, and 3100 m/s) are considered in this study. The goal is to study the most sensitive input parameters (impact velocity and plate thickness) on the longitudinal extension of the projectile, penetration depth and damage crater.

关键词： smoothed particle hydrodynamics     high velocity impact     sensitivity analysis    

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Ballistic behavior of plain and reinforced concrete slabs under high velocity impact

Chahmi OUCIF, Luthfi Muhammad MAULUDIN, Farid Abed

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 299-310 doi: 10.1007/s11709-019-0588-5

摘要： This work presents a numerical simulation of ballistic penetration and high velocity impact behavior of plain and reinforced concrete slabs. In this paper, we focus on the comparison of the performance of the plain and reinforced concrete slabs of unconfined compressive strength 41 MPa under ballistic impact. The concrete slab has dimensions of 675 mm × 675 mm × 200 mm, and is meshed with 8-node hexahedron solid elements in the impact and outer zones. The ogive-nosed projectile is considered as rigid element that has a mass of 0.386 kg and a length of 152 mm. The applied velocities vary between 540 and 731 m/s. 6 mm of steel reinforcement bars were used in the reinforced concrete slabs. The constitutive material modeling of the concrete and steel reinforcement bars was performed using the Johnson-Holmquist-2 damage and the Johnson-Cook plasticity material models, respectively. The analysis was conducted using the commercial finite element package Abaqus/Explicit. Damage diameters and residual velocities obtained by the numerical model were compared with the experimental results and effect of steel reinforcement and projectile diameter were studies. The validation showed good agreement between the numerical and experimental results. The added steel reinforcements to the concrete samples were found efficient in terms of ballistic resistance comparing to the plain concrete sample.

关键词： Johnson-Holmquist-2     Johnson-Cook     reinforced concrete     damage     impact loads    

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Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1349-1358 doi: 10.1007/s11709-020-0650-3

摘要： A theoretical solution is aimed to be developed in this research for predicting the failure in internally pressurized composite pressure vessels exposed to low-velocity impact. Both in-plane and out-of-plane failure modes are taken into account simultaneously and thus all components of the stress and strain fields are derived. For this purpose, layer-wise theory is employed in a composite cylinder under internal pressure and low-velocity impact. Obtained stress/strain components are fed into appropriate failure criteria for investigating the occurrence of failure. In case of experiencing any in-plane failure mode, the evolution of damage is modeled using progressive damage modeling in the context of continuum damage mechanics. Namely, mechanical properties of failed ply are degraded and stress analysis is performed on the updated status of the model. In the event of delamination occurrence, the solution is terminated. The obtained results are validated with available experimental observations in open literature. It is observed that the sequence of in-plane failure and delamination varies by increasing the impact energy.

关键词： composite pressure vessel     low-velocity impact     failure     theoretical solution     progressive damage modeling    

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Comparison of droplet distributions from fluidic and impact sprinklers

Xingye ZHU,Shouqi YUAN,Junping LIU,Xingfa LIU

《农业科学与工程前沿（英文）》 2015年 第2卷 第1期   页码 53-59 doi: 10.15302/J-FASE-2015049

摘要： To adapt to the trend toward low-energy precision irrigation, the droplet distributions for two new prototype sprinklers, outside signal sprinkler (OS) and fluidic sprinkler (FS), were compared with impact sprinkler (IS). A laser precipitation monitor was used to measure the droplet distributions. Droplet size and velocity distributions were tested under four operating pressures for nozzles 1.5 m above the ground. For the operating pressures tested, the mean OS, FS and IS droplet diameters ranged from 0 to 3.4, 0 to 3.5, 0 to 4.0 mm, respectively. The mean OS and FS droplet velocities ranged from 0 to 6.3 m·s , whereas IS ranged from 0 to 6.3 m·s . Being gas-liquid fluidic sprinklers, droplet distributions of the OS and FS were similar, although not identical. IS mostly produced a 0.5 mm larger droplet diameter and a 0.5 m·s greater velocity than OS and FS. A new empirical equation is proposed for determination of droplet size for OS and FS, which is sufficiently accurate and simple to use. Basic statistics for droplet size and velocity were performed on data obtained by the photographic methods. The mean droplet diameter (arithmetic, volumetric and median) decreased and the mean velocity increased in operating pressure for the three types of sprinkler.

关键词： outside signal sprinkler     fluidic sprinkler     impact sprinkler     sprinkler irrigation     droplet size     droplet velocity    

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Tests on impact effect of partial fracture at steel frame connections

CHEN Yiyi, BIAN Ruoning

《结构与土木工程前沿（英文）》 2008年 第2卷 第4期   页码 295-301 doi: 10.1007/s11709-008-0049-z

摘要： Impact effect of sudden fracture at steel frame connections under severe earthquake or other extreme loads is presented in this paper. The relation of impulse caused by structural fracture to the release of inner force at the cracked location, the magnitude of the response to impact on the basis of one degree of freedom model, and the ratio of the peak value of response to natural period of the system are investigated. Two types of fracture tests were designed and carried out both on uniaxial steel bar tensioned and moment resistant steel frame model. It is proven that the response during the fracture process can be measured quite well using high-frequency data processing system. It is also revealed that the instant fracture of structural connection is characterized by progressive and partial fracture. Numerical evaluation of the impact effect of connection fracture is carried out.

关键词： structural fracture     natural     fracture     progressive     high-frequency    

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Safety and serviceability assessment for high-rise tower crane to turbulent winds

Zhi SUN, Nin HOU, Haifan XIANG

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 18-24 doi: 10.1007/s11709-009-0009-2

摘要： Tower cranes are commonly used facilities for the construction of high-rise structures. To ensure their workability, it is very important to analyze their response and evaluate their condition under extreme conditions. This paper proposes a general scheme for safety and serviceability assessment of high-rise tower crane to turbulent winds based on time domain buffeting response analysis. Spatially correlated wind velocity field at the location of the tower crane was first simulated using an algorithm for generating the time domain samples of a stationary, multivariate stochastic process according to some prescribed spectral density matrix. The buffeting forces applied to the structure were computed according to the above-simulated wind velocity fluctuations and the lift, drag, and moment coefficients obtained from a CFD computation. Those spatially correlated loads were then fed into a well calibrated finite element model and the nonlinear time history analysis was conducted to compute structural buffeting response. Compared with structural on-site response measurement, the computed response using the proposed method has good precision. The proposed method is then adopted for analyzing the buffeting response of an in-use tower crane under the design wind speed and the maximum operational wind speed for safety and serviceability assessment.

关键词： tower crane     buffeting response     wind velocity     modeling    

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Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿（英文）》 2014年 第8卷 第1期   页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要： The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词： horizontal stress index     shear wave velocity     flat dilatometer test     cone penetration test    

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Impact of anthropogenic heat emissions on meteorological parameters and air quality in Beijing usinga high-resolution model simulation

《环境科学与工程前沿（英文）》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1478-3

摘要：

The Large scale Urban Consumption of energ Y model was updated and coupled with WRF.

关键词： Anthropogenic heat emissions     LUCY     High-resolution     Meteorological parameters     Air quality    

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Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

GU Xin, ZANG Shusheng, GE Bing

《能源前沿（英文）》 2008年 第2卷 第2期   页码 140-144 doi: 10.1007/s11708-008-0037-y

摘要： To examine the effect of the flow field within the recirculation zone on flame structure, the characteristic velocity fields of methane/humid air flame in non-premixed combustion behind a disc bluff-body burner were experimentally studied by particle image velocimeter (PIV).The results show that two stagnation points exist on the centerline in the recirculation zone flame. However, the distance of the two stagnation points in humid air combustion shortens, and the minimal dimensionless velocity increases compared with the conventional non-humid air combustion. In addition, the positional curves of the minimal velocities can be partitioned into three phases representing three different flame patterns. The analysis of axial minimal velocities on the centerline and their positions under different co-flow air velocity conditions reveals that fuel-to-air velocity ratio is the crucial parameter that governs humid air combustion flame characteristics.

关键词： distance     bluff-body     fuel-to-air velocity     stagnation     parameter    

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Imaging studies of in-cylinder HCCI combustion

Pawel LUSZCZ, Hongming XU, Mirek WYZSNSKI, Xiao MA, Rob STEVENS, Athanasios TSOLAKIS

《能源前沿（英文）》 2011年 第5卷 第3期   页码 313-321 doi: 10.1007/s11708-011-0154-x

摘要： An optically accessed, single cylinder engine operated in homogenous charge compression ignition (HCCI) mode with negative valve overlap (NVO) strategy was used to perform combustion processes diagnostics under premixed conditions corresponding to the low load regime of the HCCI operational envelope. The aforementioned processes analysis was conducted utilizing synchronized simultaneous combustion event crank-angle resolved images, acquired through piston crown window with in-cylinder pressure recording. This investigation was carried out for one-step ignition fuel—standard gasoline, fuel proceeding single-stage ignition process under conditions studied. The initial combustion stage is characterized by a maximum local reaction spreading velocity in the range of 40–55 m/s. The later combustion stage reveals values as high as 140 m/s in case of stoichiometric combustion. The mixture as well as combustion stages effects are pronounced in these observed analytical results.

关键词： high speed imaging     combustion     homogenous charge compression ignition (HCCI)     reaction spreading velocity    

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NO oxidation over Co-La catalysts and NO

Tiejun Zhang,Jian Li,Hong He,Qianqian Song,Quanming Liang

《环境科学与工程前沿（英文）》 2017年 第11卷 第2期 doi: 10.1007/s11783-017-0906-x

摘要： The Co-La catalyst (pH= 1) exhibited maximum NO conversion of 43% at 180°C. Acid modified catalyst enhanced the resistance to SO . The formed sulfates may block the pore structure of the catalyst. The NO conversion of compact SCR was 91% at 180°C at the highest space velocity. A series of Co-La catalysts were prepared using the wet impregnation method and the synthesis of catalysts were modified by controlling pH with the addition of ammonium hydroxide or oxalic solution. All the catalysts were systematically investigated for NO oxidation and SO resistance in a fixed bed reactor and were characterized by Brunanuer–Emmett–Teller (BET) method, Fourier Transform infrared spectroscopy (FTIR), X–ray diffraction (XRD), Thermogravimetric (TG) and Ion Chromatography (IC). Among the catalysts, the one synthesized at pH= 1 exhibited the maximum NO conversion of 43% at 180°C. The activity of the catalyst was significantly suppressed by the existence of SO (300 ppm) at 220°C. Deactivation may have been associated with the generation of cobalt sulfate, and the SO adsorption quantity of the catalyst might also have effected sulfur resistance. In the case of the compact selective catalytic reduction (SCR), the activity increased from 74% to 91% at the highest gas hourly space velocity (GHSV) of 300000 h when the NO catalyst maintained the highest activity, in excess of 50% more than that of the standard SCR.

关键词： NO catalytic oxidation     pH effect     Low temperature     Sulfur dioxide     High space velocity     SCR    

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Design and characteristics of electric supercharger for diesel engine acceleration by additional rapid air injection

YAO Chun-de, ZHOU Hong-xiu

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 409-412 doi: 10.1007/s11465-006-0048-5

摘要： The ES (electric supercharger) driven by a high-speed brushless motor was developed to solve the problem of smoke caused by the turbocharger s sluggish response during acceleration. Its rotation speed was from 6 000 r/min to 24 000 r/min, and the maximum flux was 0.1 kg/s. The structural design of the electric supercharger is novel, which makes it easier to set the lubricating installation and to assemble. The velocity distribution at the outlet of the electric supercharger is determined by hot-wire anemometry under various rotation speeds in steady state. Furthermore, the trends of the flux and charge rate with various speeds were analyzed. In addition, the transient response was detected from the motor setup to smooth running within 10 s, 15 s, 20 s and 25 s respectively, and the characteristic of the transient flux is under pilot study. Research results indicate that the electric supercharger can respond rapidly with the great flux, and it is independent of the operating conditions of a diesel engine. Therefore, it is a feasible way to reduce smoke emission and improve the acceleration performance.

关键词： acceleration     velocity distribution     high-speed brushless     turbocharger     electric supercharger    

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Technology improvements and management innovations in construction of Xiluodu hydropower station on Jinsha River

Qixiang FAN

《工程管理前沿（英文）》 2017年 第4卷 第2期   页码 231-237 doi: 10.15302/J-FEM-2017103

摘要： Hongtao ZHOU, Hongwei WANG, Wei ZENG. [J]. Front. Eng, 2018, 5(1): 78-87.Peter REDFERN, Hua ZHONG. [J]. Front. Eng, 2017, 4(2): 193-200.Ming-zhou Liu,Cong-hu Liu,Mao-gen Ge,Yuan Zhang,Qing-hua Zhu. [J]. Front. Eng, 2016, 3(2): 144-146.Chong-guang Feng,Hao Hu,Feng Xu,Jian Yang. [J]. Front. Eng, 2015, 2(2): 178-181.Yu Zhao,Sheng-quan Wang,Ke-chao Zhu. [J]. Front. Eng, 2015, 2(1): 35-38.Ru-gui Chen,Jia-meng Chen. [J]. Front. Eng, 2014, 1(1): 52-61.An Wang. [J]. Front. Eng, 2014, 1(1): 13-17.

关键词： super-high arch dam     intelligent construction     mass concrete temperature control     structure behavior control     anti-erosion concrete     low-heat portland cement     large-discharge and high-velocity spillway tunnels     large scale underground powerhouse     green hydropower station     sustainable development     Xiluodu hydropower station    

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definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wave velocity

《医学前沿（英文）》 2022年 第16卷 第5期   页码 714-722 doi: 10.1007/s11684-021-0888-8

摘要： A new definition of metabolic dysfunction-associated fatty liver disease (MAFLD) has recently been proposed. We aim to examine the associations of MAFLD, particularly its discordance from non-alcoholic fatty liver disease (NAFLD), with the progression of elevated brachial-ankle pulse wave velocity (baPWV) and albuminuria in a community-based study sample in Shanghai, China. After 4.3 years of follow-up, 778 participants developed elevated baPWV and 499 developed albuminuria. In comparison with the non-MAFLD group, the multivariable adjusted odds ratio (OR) of MAFLD group for new-onset elevated baPWV was 1.25 (95% confidence interval (CI) 1.01–1.55) and 1.35 (95% CI 1.07–1.70) for albuminuria. Participants without NAFLD but diagnosed according to MAFLD definition were associated with higher risk of incident albuminuria (OR 1.77; 95% CI 1.07–2.94). Patients with MAFLD with high value of hepamet fibrosis score or poor-controlled diabetes had higher risk of elevated baPWV or albuminuria. In conclusion, MAFLD was associated with new-onset elevated baPWV and albuminuria independently of body mass index, waist circumference, and hip circumference. Individuals without NAFLD but diagnosed as MAFLD had high risk of albuminuria, supporting that MAFLD criteria would be practical for the evaluation of long-term risk of subclinical atherosclerosis among fatty liver patients.

关键词： metabolic dysfunction-associated fatty liver disease     non-alcoholic fatty liver disease     fibrosis score     brachial-ankle pulse wave velocity     albuminuria    

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Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 190-200 doi: 10.1007/s11465-019-0537-y

摘要： In recent years, the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material properties that are not naturally available. Materials featuring a specific stiffness, or structures that combine non-structural and structural functions are applied in the aerospace, electronics and medical industry fields. Particularly, structures designed for dynamic actuation with reduced vibration response are the focus of this work. The bi-material and multifunctional concepts are considered for the design of a controlled piezoelectric actuator with vibration suppression by means of the topology optimization method (TOM). The bi-material piezoelectric actuator (BPEA) has its metallic host layer designed by the TOM, which defines the structural function, and the electric function is given by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control (AVFC). The AVFC, provided by the piezoelectric layers, affects the structural damping of the system through the velocity state variables readings in time domain. The dynamic equation analyzed throughout the optimization procedure is fully elaborated and implemented. The dynamic response for the rectangular four-noded FE analysis is obtained by the Newmark’s time-integration method, which is applied to the physical and the adjoint systems, given that the adjoint formulation is needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the displacement energy output measured at a predefined degree-of-freedom of the BPEA when a transient mechanical load is applied. Results are obtained for different control gain values to evaluate their influence on the final topology.

关键词： topology optimization method     bi-material piezoactuator     active velocity feedback control     time-domain transient analysis     host structure design     vibration suppression    

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标题 作者 时间 类型 操作

High velocity impact of metal sphere on thin metallic plate using smooth particle hydrodynamics (SPH)

Hossein ASADI KALAMEH, Arash KARAMALI, Cosmin ANITESCU, Timon RABCZUK

期刊论文

Ballistic behavior of plain and reinforced concrete slabs under high velocity impact

Chahmi OUCIF, Luthfi Muhammad MAULUDIN, Farid Abed

期刊论文

Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

期刊论文

Comparison of droplet distributions from fluidic and impact sprinklers

Xingye ZHU,Shouqi YUAN,Junping LIU,Xingfa LIU

期刊论文

Tests on impact effect of partial fracture at steel frame connections

CHEN Yiyi, BIAN Ruoning

期刊论文

Safety and serviceability assessment for high-rise tower crane to turbulent winds

Zhi SUN, Nin HOU, Haifan XIANG

期刊论文

Prediction of the shear wave velocity

Amoroso SARA

期刊论文

Impact of anthropogenic heat emissions on meteorological parameters and air quality in Beijing usinga high-resolution model simulation

期刊论文

Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

GU Xin, ZANG Shusheng, GE Bing

期刊论文

Imaging studies of in-cylinder HCCI combustion

Pawel LUSZCZ, Hongming XU, Mirek WYZSNSKI, Xiao MA, Rob STEVENS, Athanasios TSOLAKIS

期刊论文

NO oxidation over Co-La catalysts and NO

Tiejun Zhang,Jian Li,Hong He,Qianqian Song,Quanming Liang

期刊论文

Design and characteristics of electric supercharger for diesel engine acceleration by additional rapid air injection

YAO Chun-de, ZHOU Hong-xiu

期刊论文

Technology improvements and management innovations in construction of Xiluodu hydropower station on Jinsha River

Qixiang FAN

期刊论文

definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wave velocity

期刊论文

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

期刊论文