Construction Technique Analysis and Improvement for Rammed Earth Wall of Rural Houses in Hanzhong

Rammed earth wall technique is one of the local widespread traditional construction methods, and it has superior physical property and ecological protection characteristic. When contemporary raw-soil building is replaced by industry building, the hometown building culture is perishing gradually. In order to inherit and develop the Hanzhong local building, rammed earth wall in Taiyangling and Cangshe hometown is investigated, and the characteristics and construction techniques of the local rammed earth wall are concluded. According to the construction problems, the improvement suggestions are put forward, which establishes the foundation to investigate rammed earth wall further, and guide Rural House construction.

Site Test of Thermal Environment of Rammed Earth Construction in Anji County of China

The scientific evaluation on heat insulation and preservation capacity of rammed earth construction can provide an effective evidence for its superiority in preserving thermal environment of the construction. By taking an eco-hotel in Zhejiang Anji County as the research object, 33 test points have been set. The indoor and outdoor air temperature of eco-hotel and the surface temperature of building envelopes had been recorded by using data acquisition instrument, temperature transmitter and other equipments from January 27 to February 2 in 2007. Then, the data of a period had been selected for comparison and analysis and the results had been obtained as follows. In January when the temperature difference between day and night in Anji was not large, without particular thermal insulation measures and equipments, the indoor temperature of eco-hotel fluctuated very little, showing that rammed earth construction was of obvious capacity for heat preservation and insulation, that its heat stability was evident and that it could ensure excellent indoor thermal environment.

Experimental Study of Dynamic Characteristics on Composite Foundation with CFG Long Pile and Rammed Cement-Soil Short Pile

Based on the idea of optimization design of pile type, the two kinds of the typical pile type are selected, which containing flexibility pile (e.g. rammed cement-soil pile is for short RCSP), and rigid pile (e.g. cement-flyash-gravel pile is for short CFGP). The three kinds of the composite foundation are designed, which are CFGP, CFG long pile and CFG short pile (for short CFGLP-CFGSP), CFG long-short pile and rammed cement-soil short pile (for short CFGLP-RCSSP). Natural earthquake is simulated by using the engineering blasting;the dynamic characteristics and dynamic response of the composite foundation are studied through field test. CFGLP-RCSSP is closed to linear relation. The bearing capacity of the four composite foundation of the CFGP, CFGLP-CFGSP, and CFGLP-RCSSP in the site are 225 kPa, 179 kPa, and 197 kPa, separately increases 150%, 98.8% and 119% compared to the natural foundation. The vibration main frequency is mainly depended on properties of foundation soil and piles between vibration source and measuring point, pilling load value. Horizontal vibration main frequency greater than the vertical vibration main frequency and the vertical vibration main frequency close to the first-order natural frequency of composite foundation. With the pilling load increasing, the CFGLP-RCSSP pile composite foundation combined frequency decreased. Under the same blast energy, the acceleration peak on the CFG pile composite foundation is less than CFGLP-CFGSP the corresponding values, as the load increases, the peak acceleration gently. CFG pile composite foundation is favorable on seismic. The distribution of peak acceleration is consistent within 4 m from pile top in the CFGLP_RCSSP composite foundation. The maximum of the horizontal acceleration peak along the pile body occurs at a distance of pile top 4 m or the pile top, and that of vertical acceleration peak occurred at a pile top.

Engineering Properties of Unstabilized Rammed Earth with Different Clay Contents

The physical and mechanical properties of unstabilized rammed earth with different clay contents were studied, which could provide a theoretical basis for the understanding of mechanical properties of unstabilized rammed earth and improve the construction design method and specification of RE buildings for sustainable development. The experimental results show that clay content has significant influences on the engineering properties of unstabilized rammed earth. For the fine-grained soil, the liquid limit, plastic limit and plasticity index increase gradually with the increase of the clay content. The influence of clay content on the optimum moisture content compared with the maximum dry density is more significant. The mechanical properties of unstabilized rammed earth are significantly affected by the clay content. There exist good linear relationships, which can be used for the mutual verification or calculation among the mechanical properties. An empirical model of unconfined compression strength with the FA/CA ratio as the main parameter is established, and the UCS may obtain the maximum with a FA/CA ratio of 5.77.

Corrigendum to “Optimizing the evolution of strength for lime-stabilized rammed soil” [J Rock Mech Geotech Eng 11(2019)882-891]

The authors regret that in the paper of Baldovino et al.(2019),published in Journal of Rock Mechanics and Geotechnical Engineering(JRMGE),Eq.(2)must be corrected.Eq.(2)in the original paper describes a formula to calculate the unconfined compressive strength(q_u).But Authors wrote it as if it were the formula for calculating the split tensile strength(qt).To amend this error,Eq.(1)and Eq.(2)are the correct expressions for q_u and q_t measurements,respectively.

RECOMMENDATIONS FOR THE SELECTION,STABILIZATION,AND COMPACTION OF SOIL FOR RAMMED EARTH WALL CONSTRUCTION

Rammed earth possesses environmental advantages over most other competing construction materials.However,if it is to be more routinely used in the construction of modern,sustainable buildings,its material properties and produc-tion processes must be properly quantified.This paper proposes practical recommendations for soil selection,stabilizer treatment,and on-site compaction for rammed earth,based on a recent set of 219 stabilization experiments.The pur-pose of the recommendations is to maximize the probability of constructing rammed earth walls that meet or exceed a compressive strength criterion of 2 MPa.The recommendations cover:(1)Quantifying the natural soil properties of linear shrinkage and texture in a staged sequence in order to identify suitable soils to stabilize(and to reject unsuit-able soils);(2)Quantifying the amounts of cement and/or lime to be added to the selected soil according to the values of soil properties measured;and(3)Quantifying the forces involved in on-site compaction of stabilized soil(for both manual and pneumatic ramming),and relating these to laboratory-based test standards.Although the recommenda-tions need to be tested and verified/refined using new data,their initial application to rammed earth construction situations in Australia indicates that they have predictive utility.Further research will also indicate the degree of applicability of the recommendations to the production of compressed earth bricks.

一种使用Flash阵列存储数据的方法研究

在航空航天领域,随着飞行器性能的提升,研制过程中试验所需的数据存储量和数据存储速度也在不断提高。该文基于高速大容量数据存储的目的,利用FPGA的强大数据处理能力,进行Flash存储阵列及流水线管理的设计,并针对Flash阵列坏块检测和突发坏块提出了对应处理方法。通过对不同组合方式的存储阵列速度及存储容量进行研究对比,得到了一种使用Flash阵列进行高速数据存储的设计方法。相较单片存储,设计的存储阵列数据存储容量和速度成倍增加,且存储阵列的有效块利用率在99%以上。

基于改进平方根无迹粒子滤波的RAM类目标跟踪

RAM类目标运动复杂,对跟踪系统提出了更高的要求。针对粒子滤波在解决RAM类目标跟踪过程中存在的粒子退化等问题,通过无迹变换计算得出后验概率密度函数充当粒子滤波的先验概率密度函数,提高后验概率密度函数拟合程度,最终提高粒子的有效性。同时,在无迹变换过程中采用qr分解取代部分Cholesky分解,使输出信号方差矩阵保持非负性。最后,针对一段RAM类目标轨迹建立动力学模型,通过Matlab进行仿真,验证了该算法的有效性。

Enhanced structural damage behavior of liquid-filled tank by reactive material projectile impact

A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles(RMPs) impacting liquid-filled tanks,and the corresponding hydrodynamic ram(HRAM) was studied in detail.PTFE/Al/W RMPs with steel-like and aluminum-like densities were prepared by a pressing/sintering process.The projectiles impacted a liquid-filled steel tank with front aluminum panel at approximately 1250 m/s.The corresponding cavity evolution characteristics and HRAM pressure were recorded by high-speed camera and pressure acquisition system,and further compared to those of steel and aluminum projectiles.Significantly different from the conical cavity formed by the inert metal projectile,the cavity formed by the RMP appeared as an ellipsoid with a conical front.The RMPs were demonstrated to enhance the radial growth velocity of cavity,the global HRAM pressure amplitude and the front panel damage,indicating the enhanced HRAM and structural damage behavior.Furthermore,combining the impact-induced fragmentation and deflagration characteristics,the cavity evolution of RMPs under the combined effect of kinetic energy impact and chemical energy release was analyzed.The mechanism of enhanced HRAM pressure induced by the RMPs was further revealed based on the theoretical model of the initial impact wave and the impulse analysis.Finally,the linear correlation between the deformation-thickness ratio and the non-dimensional impulse for the front panel was obtained and analyzed.It was determined that the enhanced near-field impulse induced by the RMPs was the dominant reason for the enhanced structural damage behavior.

浸没燃烧式气化器SCV的RAM分析及可用度优化

浸没燃烧式气化器(SCV)是液化天然气LNG应急调峰站的关键核心系统,系统中出现设备故障会导致天然气供应中断,将造成显著社会影响与生产损失。为了评估SCV系统的生产性能及提高运行稳定性,提出并建立SCV-RAM分析模型,应用蒙特卡洛模拟仿真定量辨识SCV的瓶颈单元设备并针对性设计改进方案。结果表明,SCV系统易发生故障的单元按贡献度依次分别是:助燃空气单元、循环冷却水单元,其中导致系统不可用度增大的具体关键设备为水泵、电机以及鼓风机。据此对关键设备的预防性维修间隔进行优化,SCV系统的全寿命周期统计可用度从90.17%提高到94.93%,总停机时间减少了3478h。分析结果有助于优化SCV系统的维修资源分配,为实现SCV系统长周期稳定运行提供技术支持。

多腔梯度序贯充压联合Caprini RAM量表指导下的康复方案对肺癌患者术后深静脉血栓的影响

目的探讨多腔梯度序贯充压联合Caprini RAM量表指导下的康复方案对肺癌患者术后深静脉血栓的影响。方法选择2020年1月-2023年1月我院收治的肺癌患者150例,将2020年1月-2021年12月收治的75例患者列为常规组,2022年1月-2023年1月收治的75例患者列为观察组。常规组实施多腔梯度序贯充压治疗与传统护理,观察组实施多腔梯度序贯充压联合Caprini RAM量表指导下的康复方案。观察两组DVT预防知识、结局相关指标和护理满意度。结果观察组干预后DVT预防知识得分明显高于常规组,患者下肢DVT发生率、D-二聚体、下肢周径差均明显低于常规组,住院时间短于常规组(P<0.05),观察组护理满意度明显高于常规组(P<0.05)。结论多腔梯度序贯充压联合Caprini RAM量表指导下的康复方案可提高肺癌患者术后DVT预防知识水平,促进康复进程,提升患者满意度。

新型列控系统ATP车载设备开发过程安全控制措施研究

作为下一代列控系统的重要组成部分,新型列控ATP车载设备的设计开发需严格按照行业技术要求执行安全控制措施,以确保设备满足安全需求。从RAMS分析、系统测试、验证确认3个方面对设备开发过程中的安全控制措施展开研究:根据新型列控ATP车载设备的功能分析,采用Relex Studio建立可靠性框图及故障树模型,计算设备的RAMS等各指标符合技术条件要求;针对系统测试需求,设计测试流程,搭建仿真测试环境进行系统测试;通过具体验证活动与多种确认方法,验证新型列控ATP车载设备能够在目标环境中有效运行。新型列控ATP车载设备所采取的安全控制措施可提高其可靠性与安全性,为其他安全相关的铁路信号设备的设计开发提供参考。

浅析基于RAMS的轨道交通车辆状态评估方法

随着轨道交通的快速发展,对其关键部件可靠性、可用性、安全性以及维修性的评估方法提出了更高的要求。因此提出了基于RAMS的轨道交通车辆状态评估方法,应用RAMS对关键部件进行状态评估,其中利用安全性确定部件维修方式,可靠性确定部件维修时间间隔,可用性判断部件维修状态。

基于双口RAM接收并处理1553B总线数据的方法研究

为了保证主机板和1553B板通过双口RAM(Random Access Memory,随机存取存储器)进行1553B总线通信时的正确性和可靠性,提出了一种利用双口RAM接收并处理1553B总线数据的方法,用于实现1553B的BC(Bus Controller,总线控制器)功能。该方法对双口RAM中的地址按照子地址号进行地址分配,通过建立相同子地址序号的数据链表和建立环形缓冲区,完美解决了发送BC→RT(Remote Terminal,远程终端)报文时相同子地址数据覆盖和主机端发送的子地址序号顺序与1553B板端发送的子地址序号顺序不一致等问题。

基于FPGA的异步双端口RAM芯片原型验证研究

为保证芯片功能符合预期,提高流片成功率,异步双端口RAM芯片设计在流片前进行充分的功能验证,其中FPGA原型验证能够重现芯片的实际工作环境,以此验证芯片设计的有效性。基于FPGA的异步双端口RAM芯片原型验证根据芯片定义,选择使用Intel公司的10M40DCF256FPGA为核心硬件搭建FPGA原型验证平台,在平台上通过完成从ASIC到FPGA的代码移植实现芯片原型,然后根据设计需求编写测试程序实现对该芯片的FPGA原型验证。测试结果均符合预期,表明异步双端口RAM芯片的功能符合设计需求,避免项目时间和资金成本的额外增加。

Micromorphological description of vernacular cob process and comparison with rammed earth

Past builders have developed very low-embodied energy construction techniques optimizing the use of local building materials.These techniques are a source of inspiration for modern sustainable building.Unfortunately,this know-how was orally transmitted and was lost as earth construction fell into disuse during the 20th century in European countries.The absence of written documents makes necessary to use an archaeological approach in order to rediscover these construction strategies.Micromorphological analysis of thin sections collacted in earth building walls was used for the first time to describe cob construction technique and highlighted several typical pedofeatures allowing to clearly identifying this process.Finally,a first comparison of the cob and rammed earth micromorphological features permitted to identify two key factors to distinguish these two techniques,the manufacturing state(solid or plastic)and the organization of the material in the wall.

轨道交通装备制造企业的RAMS体系分析

本文以轨道交通装备制造企业RAMS体系为研究对象,论述了建立RAMS体系的必要性,分析了轨道交通装备制造企业RAMS体系管理组织、体系文件和审核等要素,对轨道交通装备制造企业RAMS体系落实情况进行了简要分析,为轨道交通装备制造企业完善RAMS体系、建立切实有效的执行方法提供了参考。

Research on the historical and cultural value of and protection strategy for rammed earth watchtower houses in Chongqing,China

Chinese watchtower houses are part of the unique human cultural heritage of the world’s vernacular architectures.Many earthen manor watchtower houses in Chongqing,China,have absorbed the characteristics of other tower houses across the country and have brought together various types of watchtower construction techniques.They are important connection points for the integrity of the Chinese watchtower house as a comprehensive architectural cultural heritage system.They can be a typical sample of Chinese Han classical towers.These buildings are indispensable parts of the Chinese residential watchtower system and have important cultural protection value.However,due to the general lack of excavation and attention to their historical and cultural value,these buildings are on the verge of disappearing.Although they have lost their original architectural functions,they have important value in terms of their building materials,technical composition and artistic modelling.They can stimulate special emotional resonance and become an important bridge that maintains the cultural connection between ancient and modern humans.Therefore,discussing the historical and cultural value of Chongqing rammed earth watchtower houses,the strategy for heritage protection and utilisation is of far-reaching signifcance for Chinese watchtower dwellings.

一种基于FPGA的ECC点乘优化设计

现场可编程门阵列(field programmable gate array,FPGA)具有丰富的计算、存储等资源,广泛应用于密码算法、实时通信等高并行、高数据吞吐量、计算复杂的领域。现有的基于FPGA实现ECC点乘的方案,存在计算架构设计并行程度低,计算所需的逻辑资源过大的问题。针对以上问题,提出了一种基于FPGA实现ECC点乘的优化设计。通过采用RAM寻址方式设计出计算架构,并构造了一个流水线状态机,利用FPGA并行计算的优势,多次并行使能调用点加、模加、模乘、模逆算法模块,实现了高效的ECC点乘操作。实验结果表明,所提出的优化设计有效地缩减了FPGA的LUT逻辑资源,并提高了ECC点乘运算的计算速度。

适用于城市轨道交通车辆的可维修性定量分析方法研究

目前,可靠性、可用性、可维修性、安全性的相关研究技术已广泛应用于城市轨道交通车辆全生命周期的各个阶段,针对可靠性与安全性的研究相对较多,而针对可维修性的研究较少,因此可用性研究工作受到了影响。以产品运营和维护为例,虽然有一些城市轨道交通运营公司已开展针对可维修性定性分析的研究工作,但针对可维修性定量分析研究工作却开展较少,主要原因是不明确可维修性定量分析需要研究哪些指标,研究结论对实际工作有何帮助。因此,文章提出了适用于城市轨道交通车辆的可维修性定量分析方法,阐述了样本收集要求、计算分析过程,并给出了研究成果在实际运营维护阶段的具体用途,可帮助城市轨道交通运营公司解决一些实际问题。