Possible estimation of resilient modulus of fine-grained soils using a dynamic lightweight cone penetrometer

Resilient modulus is an important parameter to characterise the resilient behaviour of pavement materials. Resilient modulus can be determined in the laboratory from repeated load triaxial test and is defined as the ratio of deviator stress to recoverable strain. Inherently, it is a challenge to perform repeated load triaxial tests as a routine basic test due to its complicated, time-consuming and expensive procedure; hence, several empirical approaches to estimate the resilient modulus from other soil mechanical properties – California bearing ratio, unconfined compressive strength or physical properties – have been proposed. This study has investigated the application of a dynamic lightweight cone penetrometer for the estimation of the resilient modulus in the laboratory and field conditions for some Victorian fine-grained subgrade soils. The results show the possibility to estimate the resilient modulus of fine-grained soils using the dynamic lightweight penetration index at any moisture content (MC) from optimum MC to soaked conditions.     

Quality assurance in dynamic testing

An agency concerned with the quality assurance of dynamic testing has recently been established. The following paper describes the nature and structure of this agency which is known as the DTA (Dynamic Testing Agency). The aims and philosophy of the DTA are discussed and the importance of the use of reliable experimental data in structural assessment and for the verification of theoretical predictions is emphasised.     

Quality assurance technologies for vlsi manufacturing

Considering the fundamental aims of VLSI Manufacturing and objectives of the Quality Assurance and Quality Control programs, three technologies, namely Dimensional Metrology, Material Analysis, and Statistical Methods of Process Control, emerge as key to success. The bewildering array of methods, instrumentation alternatives, and process states and variables to be controlled, make Quality Assurance and control activities as complex as the VLSI manufacturing itself, and demand a long-term commitment by all management, engineering, and work force teams involved.     

呼吸机质量控制与校准

呼吸机是医疗机构必须配备和使用的高风险设备之一,呼吸机的质量控制与校准引起了医疗机构、患者、相关技术部门的重视。通过介绍呼吸机的工作原理、机器种类、工作模式、日常的保养和维护,提高广大医务工作者的理论水平和操作水平;对现有的国家标准、行业标准、校准规范的分析介绍,了解呼吸机检测的现状和特点,为开展呼吸机的检测校准提供必要的技术支持。将呼吸机纳入国家计量管理,推进呼吸机检测校准的规范化工作,建立不同呼吸机检测校准的国家量值溯源体系,规范完善医疗机构质量保障体系。     

Analysis of dynamic compressive stress induced by passing trains in permafrost subgrade along Qinghai-Tibet Railway

To investigate dynamic compressive stress characteristics and related influencing factors in the permafrost site along Qinghai-Tibet Railway (QTR), a numerical analysis was carried out using self-compiling train-rail-subgrade-site dynamic coupling program ZL-TNTLM and ZL-RNTLM, by which the effect of the vibrating load generated by passing trains on the natural permafrost table was analyzed quantitatively. The results indicate that: (1) the additional dynamic compressive stress depend directly on axle load, the vibration energy at subgrade top surface is relatively larger when vibration frequencies range from 0.5 to 10 Hz, and the dominant frequencies at the top of the natural permafrost table are confined to be less than 3 Hz; (2) the vibration-affected subgrade area is mainly limited to the oval zone of 6 m below sleepers, stress concentration phenomena occur in the vicinity of rail-supporting zone in ballast, the maximum dynamic compressive stress at the bedding superface presents a saddle-type distribution, and certain negative exponential function can be adopted to fit the attenuation relationship of the dynamic stress vs. depth; (3) the dynamic compressive stress of subgrade top surface is the largest in winter, then followed by spring and autumn, and the least in summer, while the corresponding trend is quite the opposite in the interior of subgrade; (4) the dynamic compressive stress surrounding the wide gap decreases with the rise of train speed, however vibration response tends to be stable at certain critical speed, and the critical speed decreases with depth below subgrade surface; (5) the additional dynamic stress at the natural permafrost table can be notably reduced by appropriately increasing the embankment height. The drawn conclusions can, believed by the authors, provide certain theoretical insight for the safety evaluation of QTR operation, vibratory subsidence prediction, as well as the construction of permafrost subgrade.     

高碾压混凝土坝智能碾压理论研究

给出了高碾压混凝土坝智能碾压的概念及实现过程,提出了大坝实时监控和智能反馈控制的原理;在实时分析压实指标的基础上,建立了大坝压实质量多元回归模型,进而提出了碾压混凝土坝压实度全仓面实时评价方法;实现了施工过程中碾压机工作性态的自适应调整,确保碾压机速度、激振力、碾压遍数和压实厚度等全过程达标,可有效保证碾压质量,提高施工效率,为碾压混凝土坝建设质量控制提供了一条新的途径。     

Integrated dynamic single item lot-sizing and quality inspection planning

This paper proposes an integrated model for single item dynamic lot-sizing problem and Quality Inspection Planning (QIP). The objective is to provide a model of production planning that takes into account a targeted level of outgoing quality or an Acceptable quality level (AQL) when the manufacturing system inherently generates a proportion of defectives that increases significantly when the system switches from the in-control state to the out-of-control state. The average outgoing quality of each period of time of the planning horizon is bounded as a function of the inspection capacity. The effects of integrating QIP are analysed and discussed through several experiments representing different quality control system’s parameters, i.e. inspection capacity, inspection cost and AQL. The simulation results show that it is very important to take into account the inspection process into production planning decisions. This study will help the decision-makers to negotiate service levels or react properly to given customer quality requirements based on cost and lead time parameters in addition to their process characteristics in terms of capability and stability.     

A RFID-based recursive process mining system for quality assurance in the garment industry

With the increasing concern about product quality, attention has shifted to the monitoring of production processes to be assured of good quality. Achieving good quality is a challenging task in the garment industry due to the great complexity of garment products. This paper presents an intelligent system, using fuzzy association rule mining with a recursive process mining algorithm, to find the relationships between production process parameters and product quality. The goal is to derive a set of decision rules for fuzzy logic that will determine the quantitative values of the process parameters. Learnt process parameters used in production form new inputs of the initial step of the mining algorithm so that new sets of rules can be obtained recursively. Radio frequency identification technology is deployed to increase the efficiency of the system. With the recursive characteristics of the system, process parameters can be continually refined for the purpose of achieving quality assurance. A case study is described in which the system is applied in a garment manufacturing company. After a six-month pilot run of the system, the numbers of critical defects, major defects and minor defects were reduced by 7, 20 and 24%, respectively while production time and rework cost improved by 26 and 30%, respectively. Results demonstrate the practical viability of the system to provide decision support for garment manufacturers who may not be able to determine the appropriate process settings for achieving the desired product quality.     

Quality control results of the drift tubes for the ATLAS MDT-BIS chambers

ATLAS (A Toroidal LHC ApparatuS) is a general purpose experiment, which will start its operation at the Large Hadron Collider (LHC) at CERN in 2007. The ATLAS detector is designed to study the products of proton–proton collisions at c.m.s. energies of up to 14 TeV. Three Greek Universities have taken the responsibility to construct 112 BIS-MDT (Barrel Inner Small) chambers using 29 000 drift tubes of 170 cm length and 3 cm diameter that have been quality tested before assembly. This work describes the Quality Assurance and Quality Control (QA_QC) procedures for the drift tubes, followed at the High Energy Physics Laboratory of the National Technical University of Athens, while emphasis is given on the obtained results for the above mentioned number of tubes.     

Design of an integrated quality assurance strategy in production systems

High-quality of products is a critical issue for manufacturers to maintain their competitiveness in global markets. For this reason, more attention has been paid by operations managers and academics to the design of quality assurance strategies, acceptance sampling plans and inspection allocation problems. In the last decades, international research has studied and introduced several models and approaches to investigate these issues. The purpose of this paper is to provide a new methodology for designing and selecting correct integrated quality assurance strategies, defining cost models for acceptance policies and inspection station configurations. Generally, high-quality of items is guaranteed by avoiding defects, mainly caused by non-conforming components, resulting from instantaneous and standard infant mortality. Thus, an optimal acceptance policy is defined in order to reduce the instantaneous infant mortality defects. A closed-form equation has been introduced to determine easily and quickly the optimal percentage of checked items. Furthermore, a more convenient inspection station configuration is determined in order to minimise the expected total cost, composed of testing, inspection and penalty cost elements. The innovative concept of defect rate as an inspection time variable dependent has been introduced. The impact of different economic and survival parameters on designing inspection policies is also investigated. Finally, a real-life case study demonstrates the applicability of this methodology in real production systems and several considerations are reported about the future research, that the authors will carry out.     

Cultural heritage in project management: project appraisal and quality assurance in the early phase of major public investments

This paper is an analysis of how cultural heritage values are handled in documentation related to early phase evaluations of major public investment projects in Norway. This study was instigated by an apparent lack in the consideration of cultural heritage values in such documentation. We conducted a case study document analysis to see how cultural heritage issues are addressed in the early phases of projects. Methodologically, the paper analyses the use of vocabulary related to cultural heritage values in the documentation. There is uniform documentation available from these projects. The results suggest that cultural heritage values are mentioned but seldom substantially discussed in the documents. Cultural heritage values tend to be discussed using non-specific language. There is an emphasis on legislation regarding cultural heritage and how the legislation can be a problem. Today’s discussion of cultural heritage values appears to be lacking and in need of a strengthened framework. The methodology applied in this study aims to provide a structured search method for the unstructured discussion of cultural heritage issues in these extensive documents.     

The application of the Six Sigma concept to port security process quality control

Greater heed has been paid to the matter of maritime security since the tragedy in the U.S.A. on 11 September 2001. A number of measures have been put into practice by ports to enhance security. More regulations and measures sometimes imply an increased probability of influencing port operations. Thus, the quality of the port security process regulated by measures is becoming essential. In this paper, the quality control in the port security process is demonstrated using the Six Sigma concept. It is concluded that it is crucial to distinguish each step of a security process clearly from the outset, furthermore, gathering quantitative data at each stage is the first priority. Copyright © 2007 John Wiley & Sons, Ltd.     

Quality assurance and quality control methodologies used within the Austrian UV monitoring network

The Austrian UVB monitoring network is operational since 1997. Nine detectors for measuring erythemally weighted solar UV irradiance are distributed over Austria in order to cover the main populated areas as well as different levels of altitude. The detectors are calibrated to indicate the UV-Index, the internationally agreed unit for erythemally weighted solar UV irradiance. Calibration is carried out in the laboratory for determination of spectral sensitivity of each detector, and under the sun for absolute comparison with a well-calibrated, double-monochromator spectroradiometer. For the conversion from detector-weighted units to erythemally weighted units a lookup table is used, which is calculated using a radiative transfer model and which reflects the dependence of the conversion on the solar zenith angle and total ozone content of the atmosphere. The uncertainty of the calibration is about +/-7%, dominated by the uncertainty of the calibration lamp for the spectroradiometer (+/-4%). The long-term stability of this type of detectors has been found to be not satisfactory. Therefore, routinely every year all detectors are completely recalibrated. Variations of the calibration factors up to +/-10% are found. Thus, during routine operation, several measures take place for quality control. The measured data are compared to results of model calculations with a radiative transfer model, where clear sky and an aerosol-free atmosphere are assumed. At each site, the UV data are also compared with data from a co-located pyranometer measuring total solar irradiance. These two radiation quantities are well correlated, especially on clear days and when the ozone content is taken into account. If suspicious measurements are found for one detector in the network, a well-calibrated travelling reference detector of the same type is set up side-by-side, allowing the identification of relative differences of approximately 3%. If necessary, a recalibration is carried out. As the main aim for the Austrian UV monitoring network is the information of the public about the actual levels of UVB irradiance, the measurement results are published on-line in the Internet (http://www.uibk.ac.at/projects/uv-index). For the previous day and backwards approximately 2 years, the distribution of maximal UVB levels over Austria is shown on a regional map. Additionally, near real-time data of most of the measurement stations are presented with a delay of usually less than half-an-hour. Together with these actually measured data there is also shown the diurnal variation of the maximal expected value of the UV-Index under ideal clear conditions.     

运用系统工程满足测量设备的质量保证要求

文章运用系统工程的方法,将建立“满足石钢公司测量设备的质量保证要求”作为系统目标,将影响测量设备的质量保证要求的各种因素作为一个系统进行分析,找出主要原因并制订有效措施加以实施,解决企业计量管理工作不畅、不规范等问题,恢复了计量工作在企业质量管理中应有的地位及作用。     

Integrating failure analysis and risk analysis with quality assurance in the design phase of medical product development

Today, manufacturing operates as a global network, which has created more awareness of the quality of products and services. A systematic and rational way of managing quality assurance is currently lacking. This can cause serious problems in sectors such as the medical industry, as product failure may not only cause time delays, but also create risks for the health and safety of patients and users. This paper proposes a quality assurance approach that incorporates risk analysis (based on ISO14971) and failure analysis (based on FMEA) into the product design phase to assure product quality in the short term and facilitate global manufacturing practices in the long run. The proposed approach includes a Markov model to predict product failure from a customer perspective, which serves as a checkpoint for feedback to provide a basis for quality assurance. A medical equipment firm is used as a test-bed to illustrate how the proposed approach works and to verify its effectiveness.     

Characterising the elastic behaviour of fine-grained subgrade soils under traffic loading

Resilient modulus is a measure of the elastic behaviour of subgrade soil under traffic loading. The design thickness of a pavement structure and its predicted performance are highly dependent on subgrade modulus. Characterisation of subgrade resilient modulus involves conducting advanced repeated loading triaxial testing that requires special equipment and technical experience that are not available in many soil laboratories. The objectives of this paper were to characterise the resilient modulus of typical fine-grained subgrade soils and develop design inputs for the Mechanistic-Empirical Pavement Design Guide. The resilient modulus of subgrade soil samples was tested at different levels of moisture content. Results of the laboratory testing were used to develop prediction models for resilient modulus as function of physical properties of the subgrade soil and stress state. The proposed models were compared to those developed under the Long-Term Pavement Performance programme. The results showed that the proposed models provided more reliable predictions with lower root mean square error.     

Computational simulations of the dynamic compaction of porous media

The goal of this study was to apply and compare different computational compaction models to the dynamic compaction of porous silicon dioxide (SiO₂) powder. Three initial specific volumes were investigated in this study, V₀₀=1.3, 4 and 10 cm³/g, where the solid material specific volume is V₀=0.4545 cm³/g. Two hydrodynamic codes, KO and CTH, were used to simulate the experimental results. Two compaction models, P– and P–λ were implemented within CTH in conjunction with the Mie–Grüneisen (MG) equation of state. The snowplow (SP) compaction model was implemented within KO. In addition, the MG equation of state based on the experimentally measured Hugoniot was implemented within CTH and was compared to the data as well. One-dimensional flyer plate experiments were conducted with impact velocities ranging from 0.25 to 1.0 km/s, which corresponded to a shock incident pressure range of 0.77–2.25 GPa. The computational simulations were compared to the temporal lateral stress signatures measured with manganin gauges, placed before and after the silica powder. It was found that the MG equation of state (EOS) most accurately reproduce all of the experimental data whereas none of the compaction models accurately reproduced all of the experimental data. However, of the compaction models investigated that the P– model tended to outperform the other considered.     

不确定电液位置伺服系统的动态面跟踪控制

针对一类含有动态不确定性的双作用液压缸电液伺服系统跟踪控制问题,采用动态面控制方法设计了一个鲁棒自适应跟踪控制器.由于在逆推设计过程中加入了低通滤波器使得该方法不用对模型非线性进行多次微分,因而设计方法简化.所设计的自适应鲁棒控制器不仅能保证闭环系统的半全局渐近稳定,使得输出渐近跟踪期望轨迹;而且,跟踪误差可以通过控制器的设计参数加以调整.数字仿真结果表明,控制系统对给定位置的跟踪具有良好的动态特性,对系统的不确定性,具有较强的鲁棒性.     

Experimental investigation of the dynamic behavior of frozen clay from the Beiluhe subgrade along the QTR

The dynamic behavior of frozen clay obtained from the Beiluhe permafrost subgrade along the Qinghai-Tibet Railway (QTR) was investigated through cryo-dynamic triaxial experiments. The effects of several key factors, including temperature, moisture content, frequency and confining pressure on the dynamic behavior, were analyzed. It was found that a hyperbolic model could describe the dynamic behavior of the frozen clay well. The maximum dynamic shear modulus of the frozen soil decreases as the temperature rises and as the confining pressure decreases; the reference shear strain magnitude decreases as the temperature and confining pressure increase and as the moisture content decreases; the maximum damping ratio increases as the temperature, frequency and confining pressure increase and as the moisture content decreases. There exists a critical moisture content (around 18%) that maximizes the dynamic shear modulus; at the critical frequency (about 6 Hz), the dynamic shear modulus is at its maximum, and the reference shear strain magnitude and the damping ratio attenuation exponent are at their respective minima. Moreover, functions were proposed to quantitatively describe the relationship between frozen clay dynamic parameters and various influencing factors.