Retrofit of RC frames against progressive collapse using prestressing tendons

This study investigates the effect of prestressing tendons on the progressive collapse performance of a 6‐ and 20‐story reinforced concrete model structures. According to nonlinear static and dynamic analysis results, the analysis model structures turned out to be vulnerable to progressive collapse caused by sudden loss of a first story column. However, the RC structures reinforced by external prestressing tendons along floor girders showed stable behavior against progressive collapse. The retrofit effect increased as the initial tension and cross‐sectional area of tendons increased. The incremental dynamic analyses showed that the seismic performance of the model structure was also enhanced after the retrofit using tendons. Based on analysis results, it was concluded that the retrofit of existing buildings using prestressing tendons could be effective for increasing both progressive collapse resisting capacity and seismic performance of RC framed structures. Copyright © 2011 John Wiley & Sons, Ltd.     

Development of an innovative vertical submerged membrane bioreactor (VSMBR) for simultaneous removal of organic matter and nutrients

A novel vertical submerged membrane bioreactor (VSMBR) composed of anoxic and oxic zones in one reactor was developed in an attempt to reduce the problems concerning effective removal of pollutants from synthetic wastewater including glucose as a sole carbon source as well as membrane fouling. The optimal volume ratio of anoxic zone/oxic zone was found as 0.6. The desirable internal recycle rate and hydraulic retention time (HRT) for effective nutrient removal were 400% and 8h, respectively. Under these conditions, the average removal efficiencies of total nitrogen (T-N) and total phosphorus (T-P) were 75% and 71%, respectively, at the total chemical oxygen demand (T-COD)/T-N ratio of 10. In addition, the VSMBR showed high specific removal rates of nitrogen and phosphorus while the biomass growth yield from the reactor was about 20% of the conventional activated sludge process.     

A joint normalcy index to evaluate patients with gait pathologies in the functional aspects of joint mobility

Gait analysis using 3D motion capture systems provides joint kinematic and kinetic analysis results such as joint relative angles and moments that can be use used to evaluate the degrees of pathological gait patterns. However, the complex data produced using these 3D motion capture systems can only analyzed by experts, because the gait analysis is highly coupled to the kinematics of each joint. Therefore, several Several previous studies using gait analysis have relied on the data compression technique to represent gait deviation from the average normal profiles as a single value. Even though it is important to evaluate gait pathologies at the joint level, all these previous studies have just used a single value to evaluate the pathological gait pattern. Using just one variable for evaluation of a gait is limited in terms of determining which joint movement patterns are getting better during rehabilitation. Therefore, in this study, a method suitable for evaluating gait deviation during a gait was developed to provide three indices for the hip, knee and ankle joints. In addition, to validate the proposed method in clinical cases, experimental tests were conducted on thirty thirty-six normal walkers and six patients with cerebral palsy. Furthermore, to validate the proposed method in regards to rehabilitation, experimental tests were conducted on three classified walking groups with imposed ankle equinus constraints. The JNI for the hip joint, knee joint and ankle were 8.78 (±3.70), 2.92 (±3.25) and 8.79 (±4.38), respectively, in the normal walking group. However, these values were significantly different for the pathological walking group with cerebral palsy. The JNI of the hip joint, knee joint and ankle joint were 203.73 (±171.59), 81.23 (±52.13) and 248.39 (±149.99), respectively, for this group. There were also differences between any two of the three classified groups with imposed ankle equinus constraints. In particular, the JNI of the ankle joint was statistically different at the p<0.01 level, and this parameter clearly increased as the degree of the imposed ankle equinus was increased. These results demonstrate that the proposed JNI can be used as a scalar factor to evaluate the angular deviation of each joint in normal and patient groups. In addition, this approach can be adapted to evaluate rehabilitation and pre/post surgery.     

Development of censored data-based robust design for pharmaceutical quality by design

Robust design techniques, which are based on the concept of building quality into products or processes, are increasingly popular in many manufacturing industries. In this paper, we propose a new robust design model in the context of pharmaceutical production research and development. Traditional robust design principles have often been applied to situations in which the quality characteristics of interest are typically time insensitive. In pharmaceutical manufacturing processes, time-oriented quality characteristics, such as the degradation of a drug, are often of interest. As a result, current robust design models for quality improvement which have been studied in the literature may not be effective in finding robust design solutions. To address such practical needs, this paper develops a robust design model using censored data, which is perhaps the first attempt in the robust design field. We then study estimation methods, such as the expectation–maximization algorithm and the maximum likelihood method, in the robust design context. Finally, comparative studies are discussed for model verification via a numerical example.     

Real-time quality monitoring and control system using an integrated cost effective support vector machine

The quality monitoring and control (QMC) has been an essential process in the manufacturing industries. With the advancements in data analytics, machine-learning based QMC has become popular in various manufacturing industries. At the same time, the cost effectiveness (CE) of the QMC is perceived as a main decision criterion that explicitly accounts for inspection efforts and has a direct relationship with the QMC capability. In this paper, the cost-effective support vector machine (CESVM)-based automated QMC system (QMCS) is proposed. Unlike existing models, the proposed CESVM explicitly incorporates inspection-related expenses and error types in the SVM algorithm. The proposed automated QMCS is verified and validated using an automotive door-trim manufacturing process. Next, we perform a design of experiment to assess the sensitivity analysis of the proposed framework. The proposed model is found to be effective and could be viewed as an alternative or complementary tool for the traditional quality inspection system.

     

Corrosion and inhibition process of carbon steel in LiBr-H2O solution

Journal of Mechanical Science and Technology - Lithium bromide (LiBr)-H2O triple-effect absorption chillers are supposed to have a much higher carbon steel corrosion rate under high temperature...     

Milling contour error control using multilevel fuzzy controller

Machining contour error plays important roles in product quality. This paper presents an implementation of multilevel fuzzy controller in controlling contour errors while maintaining the desired feed rate of milling processes. The orthogonal global task frame was used to transform the tool positions from the Cartesian coordinate system to the curvilinear coordinate system. Contour error and tracking lag error calculated from the curvilinear coordinate system were used by the multilevel fuzzy controller to drive the machining axis on the Mazak VQC-15/40 vertical machining center. The contour error of the machined work piece measured by the coordinate measuring machine showed that the contour error were significantly reduced and the feed rate were regulated at the desired speed.     

Improvement of machinability of Waspaloy via laser-assisted machining

Waspaloy is a heat-resistant alloy primarily used in aircraft turbine engines, as forged turbine and compressor disk, which is difficult to machine at room temperature due to excessive tool wear and poor surface finish. Laser-assisted machining (LAM) offers the ability to machine such superalloys more efficiently by locally heating and softening the workpiece material prior to material removal and machining with a conventional single-point cutting tool. A transient, three-dimensional heat transfer model is used for modeling LAM of Waspaloy. The thermal model is validated by comparing the temperature predictions and the surface temperature measurements using an infrared camera. The machinability of Waspaloy under varying conditions is evaluated by examining tool wear, cutting forces, and surface finish. With increasing material removal temperature from room temperature to 300–400°C, the benefit of LAM is demonstrated by a 20% decrease in specific cutting energy, a two- to three-fold improvement in surface roughness, and a 50% increase in ceramic tool life over conventional machining.     

Optimization of production scheduling with time-dependent and machine-dependent electricity cost for industrial energy efficiency

In many industrialized countries, manufacturing industries pay stratified electricity charges depending on the time of day (i.e., peak-load, mid-load, and off-peak-load). In contrast, the emerging smart grid concept may demand that industries pay real-time hourly electricity costs so as to use energy most efficiently. This paper deals with the production and energy efficiency of the unrelated parallel machine scheduling problem. This method allows the decision maker to seek a compromise solution using the weighted sum objective of production scheduling and electricity usage. Reliability models are used to consider the energy cost aspect of the problem. This paper aims to optimize the weighted sum of two criteria: the minimization of the makespan of production and the minimization of time-dependent electricity costs. We suggest a hybrid genetic algorithm with our blank job insertion algorithm and demonstrate its performance in simulation experiments.     

Insight into the chemical reaction of CH2OH with NO: Formation of N-hydroxy formamide as an isocyanic acid precursor

This study has explored the potential energy surface on the chemical reaction of CH₂OH with NO by using ab initio calculation. We have found the new reaction pathway producing N-hydroxy formamide, which can further decompose to generate isocyanic acid as a reducing agent of hydrocarbons selective catalytic reduction.