Experimental and Numerical Investigation of Axial Tensile Strength of CHS X-Joints Reinforced with External Stiffening Rings

Lei Zhao,Lei Zhu,Hailin Sun,Lu Yang,Xi Chen 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.3

To study the reinforcement eff ect of the external stiff ening ring reinforced and unreinforced X-joints having a circular hollow section subjected to brace tensile load, an experimental and computer-simulated research has been done. Six full-scale X-joints are examined in this study: three reinforced specimens and three corresponding unreinforced ones. The test specimens cover diff erent brace to chord diameters ratios ( β ) of 0.25, 0.51, and 0.73. The experimental facilities and detailed parameters are presented. The experimental results including failure modes, load–displacement curves, and ultimate capacity are analyzed and compared. Two failure modes, weld failure and chord plastifi cation, are observed in the tests. The test results reveal an ultimate load enhancement in the reinforced joints by approximately 50% in comparison with the unreinforced joints and an initial stiff ness increase of 248.1% for the β of 0.25 and approximately 49–76% for the β of 0.51 and 0.73. A fi nite element model using shell elements is developed, which accurately predicts the static performance of the X-joints subjected to brace tensile load with and without external stiff ening rings.

Structural and Thermal Characteristics of a High-Nitrogen Energetic Material: G(AHDNE)

Lu, Lei,Xu, Kangzhen,Zhang, Hang,Wang, Gang,Huang, Jie,Wang, Bozhou,Zhao, Fengqi Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.7

A high-nitrogen energetic salt, 1-amino-1-hydrazino-2,2-dinitroethylene guanidine salt [G(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and guanidine hydrochloride in sodium hydroxide aqueous solution. The theoretical investigation on G(AHDNE) was carried out by B3LYP/$6-311+G^*$ method. The thermal behaviors of G(AHDNE) were studied with DSC and TG-DTG methods, and the result presents an intense exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential constant of the process are $-1060J\;g^{-1}$, $148.7kJ\;mol^{-1}$ and $10^{15.90}s^{-1}$, respectively. The critical temperature of thermal explosion of G(AHDNE) is $152.63^{\circ}C$. The specific heat capacity of G(AHDNE) was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is $314.69J\;mol^{-1}K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of G(AHDNE) was calculated to be a certain value between 60-72 s. The detonation velocity and detonation pressure were also estimated. G(AHDNE) presents good performances.

Iterative Generation Method of Arc Length Parameterized Curve Tool Path for Surface Machining from Short-Line Tool Path

Lei Lu,Jiang Han,Lian Xia,Cheng Fan,Haijun Liu,Shan Chen 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.10

To improve the application of the parametric curve tool path in surface machining, a method for generating arc-length parameterized toolpaths based on short-line toolpaths is proposed. The method first uses commercial CAM software to plan the short-line tool path. Then, the machining tool path with smooth continuous features is extracted. The smooth and continuous features are determined according to the chord length of the short-line tool path, and the extraction method is based on Chebyshev’s inequality of large numbers. After obtaining the smooth short-line trajectory, the iterative arc-length parameterized curve toolpath generation method is used to fit the discrete short-line toolpath. In the iterative process, the B-spline toolpath with parameterized chord length is obtained first. It is discretized according to the arc length difference information of the chord length B-spline. Finally, by continuously checking and inserting B-spline nodes, and fitting according to discrete points, the arc-length parameterized B-spline tool path is obtained. The feasibility of the method is verified with a part containing a sculpted surface, and two smooth arc-length parametric toolpaths are generated. In the end, the part is machined with the arc-length parameterized curve tool path.

Proposal of a Pretreatment Nomogram for Predicting Local Recurrence after Intensity-Modulated Radiation Therapy in T4 Nasopharyngeal Carcinoma: A Retrospective Review of 415 Chinese Patients

Lu-Lu Zhang,Yi-Yang Li,Jiang Hu,Guan-Qun Zhou,Lei Chen,Wen-Fei Li,Ai-Hua Lin,Jun Ma,Zhen-Yu Qi,Ying Sun 대한암학회 2018 Cancer Research and Treatment Vol.50 No.4

Purpose Local relapse-free survival (LRFS) differs widely among patients with T4 category nasopharyngeal carcinoma (NPC). We aimed to build a nomogram incorporating clinicopathological information to predict LRFS in T4 NPC after definitive intensity-modulated radiation therapy (IMRT). Materials and Methods Retrospective study of 415 Chinese patients with non-metastatic T4 NPC treated with definitive IMRT with or without chemotherapy at our cancer center between October 2009 and September 2013. The nomogram for LRFS at 3 and 5 years was generated based on multivariate Cox proportional hazards regression, and validated using bootstrap resampling, assessing discriminative performance using the concordance index (C-index) and determining calibration ability via calibration curves. Results Five-year LRFS was 88.8%. We identified and incorporated four independent prognostic factors for LRFS: ethmoid sinus invasion, primary gross tumor volume, age, and pretreatment body mass index. The C-index of the nomogram for local recurrence was 0.732 (95% confidence interval, 0.726 to 0.738), indicating excellent predictive accuracy. The calibration curve revealed excellent agreement between nomogram-predicted and observed LRFS probabilities. Risk subgroups based on total point score cutoff values enabled effective discrimination of LRFS. Conclusion This pretreatment nomogram enables clinicians to accurately predict LRFS in T4 NPC after definitive IMRT, and could help to facilitate personalized patient counselling and treatment strategies.

Experimental evaluation of an inertial mass damper and its analytical model for cable vibration mitigation

Lei Lu,Gaston A. Fermandois,Xilin Lu,Billie F. Spencer, Jr.,Yuan-Feng Duan,Ying Zhou 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6

Cables are prone to vibration due to their low inherent damping characteristics. Recently, negative stiffness dampers have gained attentions, because of their promising energy dissipation ability. The viscous inertial mass damper (termed as VIMD hereinafter) can be viewed as one realization of the inerter. It is formed by paralleling an inertial mass part with a common energy dissipation element (e.g., viscous element) and able to provide pseudo-negative stiffness properties to flexible systems such as cables. A previous study examined the potential of IMD to enhance the damping of stay cables. Because there are already models for common energy dissipation elements, the key to establish a general model for IMD is to propose an analytical model of the rotary mass component. In this paper, the characteristics of the rotary mass and the proposed analytical model have been evaluated by the numerical and experimental tests. First, a series of harmonic tests are conducted to show the performance and properties of the IMD only having the rotary mass. Then, the mechanism of nonlinearities is analyzed, and an analytical model is introduced and validated by comparing with the experimental data. Finally, a real-time hybrid simulation test is conducted with a physical IMD specimen and cable numerical substructure under distributed sinusoidal excitation. The results show that the chosen model of the rotary mass part can provide better estimation on the damper’s performance, and it is better to use it to form a general analytical model of IMD. On the other hand, the simplified damper model is accurate for the preliminary simulation of the cable responses.

Two Maternal Lineages Revealed by Mitochondrial DNA D-loop Sequences in Chinese Native Water Buffaloes (Bubalus bubalis)

Lei, Chu-Zhao,Zhang, Wei,Chen, Hong,Lu, Fan,Ge, Qing-Lan,Liu, Ruo-Yu,Dang, Rui-Hua,Yao, Yun-Yi,Yao, Li-Bo,Lu, Zi-Fan,Zhao, Zhong-liang Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.4

Little is known about the origin and genetic diversity of swamp buffaloes in China. To obtain more knowledge on genetics of the water buffalo in China, the complete mitochondrial D-loop sequences of 30 samples from 6 native types were investigated. The results revealed 12 mitochondrial haplotypes with 50 polymorphic sites. Among these polymorphic sites, there were 49 transitions and 1 transversion. The average nucleotide diversity and haplotype diversity estimated from mtDNA D-loop region in 6 Chinese water buffalo types were 0.00684 and 0.798, respectively, showing rather abundant mitochondrial genetic diversity. The Neighbor-Joining (NJ) tree of mtDNA of Chinese water buffaloes was constructed according to the 12 haplotypes. The NJ tree indicated two lineages being designated lineage A and lineage B, in which lineage A was predominant, and lineage B was at low frequency. The new lineage B was first discovered and defined in 6 Chinese water buffalo types. These results showed that two different maternal lineages were involved in the origin of domestic swamp buffaloes in China and the lineage B was probably an introgression from Southeast Asian buffaloes.

Priority-based Differentiated Service in Spectrum Mobility Game

( Bingxian Lu ),( Zhenquan Qin ),( Lei Wang ),( Liang Sun ),( Ming Zhu ),( Lei Shu ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.4

In recent years, the problem of spectrum mobility in Cognitive Radio (CR) Networks has been widely investigated. In order to utilize spectrum resources completely, many spectrum handoff techniques based on game theory have been proposed, but most studies only concern that users how to achieve better payoffs, without much attention to the diverse needs of users. In this paper, we propose a new channel-switching model based on game theory, using a prioritized approach to meet the diverse needs of users in two different modes (CQ and PS). At the same time, this paper proposes some acceleration techniques to reach the Nash equilibrium more efficiently. We evaluate the performance of the proposed schemes depending on priority using real channel availability measurements, and conclude that the channel quality function (CQ) mode provide better service for priority user but the plan-sorting (PS) mode can be more suitable in multiple priority users exist scene.

Semi-deterministic Sparse Matrix for Low Complexity Compressive Sampling

( Lei Quan ),( Song Xiao ),( Xiao Xue ),( Cunbo Lu ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.5

The construction of completely random sensing matrices of Compressive Sensing requires a large number of random numbers while that of deterministic sensing operators often needs complex mathematical operations. Thus both of them have difficulty in acquiring large signals efficiently. This paper focuses on the enhancement of the practicability of the structurally random matrices and proposes a semi-deterministic sensing matrix called Partial Kronecker product of Identity and Hadamard (PKIH) matrix. The proposed matrix can be viewed as a sub matrix of a well-structured, sparse, and orthogonal matrix. Only the row index is selected at random and the positions of the entries of each row are determined by a deterministic sequence. Therefore, the PKIH significantly decreases the requirement of random numbers, which has a complex generating algorithm, in matrix construction and further reduces the complexity of sampling. Besides, in order to process large signals, the corresponding fast sampling algorithm is developed, which can be easily parallelized and realized in hardware. Simulation results illustrate that the proposed sensing matrix maintains almost the same performance but with at least 50% less random numbers comparing with the popular sampling matrices. Meanwhile, it saved roughly 15%-35% processing time in comparison to that of the SRM matrices.

Molecular Cloning and Characterization of a Novel Calcium-dependent Protein Kinase Gene IiCPK2 Responsive to Polyploidy from Tetraploid Isatis indigotica

Lu, Beibei,Ding, Ruxian,Zhang, Lei,Yu, Xiaojing,Huang, Beibei,Chen, Wansheng Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.5

A novel calcium-dependent protein kinase gene (designated as IiCPK2) was cloned from tetraploid Isatis indigotica. The full-length cDNA of IiCPK2 was 2585 bp long with an open reading frame (ORF) of 1878 bp encoding a polypeptide of 625 amino acid residues. The predicted IiCPK2 polypeptide included three domains: a kinase domain, a junction domain (or autoinhibitory region), and a C-terminal calmodulin-like domain (or calcium-binding domain), which presented a typical structure of plant CDPKs. Further analysis of IiCPK2 genomic DNA revealed that it contained 7 exons, 6 introns and the length of most exons was highly conserved. Semi-quantitative RT-PCR revealed that the expression of IiCPK2 in root, stem and leaf were much higher in tetraploid sample than that in diploid progenitor. Further expression analysis revealed that gibberellin ($GA_3$), NaCl and cold treatments could up-regulate the IiCPK2 transcription. All our findings suggest that IiCPK2 might participate in the cold, high salinity and GA3 responsive pathways.

Economic Growth and Environmental Quality : A Case Study from Industrial Sulfur Dioxide Provincial Panel Data in China

Lei, Shi,Lu, Xing Korean Resource Economics Association 2007 자원·환경경제연구 Vol.16 No.3

The Environmental Kuznets Curve Hypothesis postulates an inverted-U shaped relationship between GDP per capita and various pollutants. Pollutants emission increases up to a certain level as income goes up; after that, it decreases. This paper investigates the relationship between industry pollutants taking industrial sulfur dioxide omission as example, and economic growth by using province-panel data set from 1989 to 2004 in 28 provinces of P. R. China. The result shows that the EKC hypothesis may be supported in the case of industrial sulfur dioxide, and the GDP per capital of turning point is about RMB 13,548 (at 1978 price). Except Shanghai, all the provinces GDP per capital in this study are less than RMB 13,548, indicating the amount of industrial sulfur dioxide emission will be increasing in the near future. To realize sustainable development and pollutants abatement, the central and local government should adopt an integrated strategy to protect environment.