-
Experimental and Numerical Study of Air Flow Diffusion and Contaminants Circulation in Room Ventilation Related with Iraqi Climate
Alaa Abbas Mahdi,
Alaa Abbas Mahdi
Issue:
Volume 4, Issue 2, April 2016
Pages:
24-42
Received:
13 February 2016
Accepted:
25 February 2016
Published:
7 March 2016
Abstract: Illnesses of many indoor air quality problems occur in office room. Ventilation is one way to control the contaminant transport and to provide better indoor air quality with in the office. In the evaluation of indoor air quality, CO2 concentration is regarded as a good indicator to estimate the air quality level and to assess the performance of a mechanical ventilation system used by many designers, So the CO2 concentration was used as the tracer gas in this study, also the humans respiration taken into account as CO2 sources were the rate of production of carbon dioxide (CO2) by human respiration. Experimental measurement and computational fluid dynamics (CFD) simulation methods were applied. The results from this study show that the floor-supply displacement ventilation can improve indoor air quality because the pollutant concentration in the breathing zone is lower than that of mixing system and the risk of cross contamination can be effectively reduced. Nevertheless, the indoor spaces with floor-supply displacement ventilation might have a higher risk of discomfort, because of high temperature stratification between the ankle and head levels when compared to traditional mixing ventilation. The results indicated that the contaminant distribution in a mechanically ventilated office room need to be studied individually according to different cases.
Abstract: Illnesses of many indoor air quality problems occur in office room. Ventilation is one way to control the contaminant transport and to provide better indoor air quality with in the office. In the evaluation of indoor air quality, CO2 concentration is regarded as a good indicator to estimate the air quality level and to assess the performance of a m...
Show More
-
Connection Between the Number of Complaints About Welding Suppliers and End Product Quality: The Case of Customized Welding Production
Jenni Toivanen,
Harri Eskelinen,
Paul Kah,
Jukka Martikainen
Issue:
Volume 4, Issue 2, April 2016
Pages:
43-49
Received:
5 February 2016
Accepted:
16 February 2016
Published:
9 March 2016
Abstract: Although undesirable, manufacturing defects leading to complaints are almost inevitable in the production of manufactured products, and consideration of manufacturing quality is therefore an essential aspect of management of supply chains with multiple suppliers. This study evaluates the relationship between complaints about the end product and welding production in a multiple supplier chain. In the studied case, it was noticed that there is potential for improved welding production management by suppliers to increase profitability by decreasing the number of welding defects that cause complaints. This study shows one approach to analysis of the relation between complaints in the supply chain and their effect on the end product.
Abstract: Although undesirable, manufacturing defects leading to complaints are almost inevitable in the production of manufactured products, and consideration of manufacturing quality is therefore an essential aspect of management of supply chains with multiple suppliers. This study evaluates the relationship between complaints about the end product and wel...
Show More
-
Cascading Failure Risk Assessment Considering Protection System Hidden Failures
Rui Hu,
Xindong Liu,
Yulong Huang,
Can Chen,
Jianfen Zhang
Issue:
Volume 4, Issue 2, April 2016
Pages:
50-58
Received:
15 February 2016
Accepted:
24 February 2016
Published:
5 April 2016
Abstract: Cascading failure plays an important role in blackouts. Complex network theory, with the disadvantage of ignoring some of physical features of the power systems, is often utilized to model the cascading failure evolution processes. In this paper, a new risk assessment method based on evolution procedure and dynamic fault trees (DFTs), is proposed to model cascading failures in power systems. DFTs, which extend standard fault tree by allowing the modeling of complex system components’ behaviors and interactions, are introduced to describe the cascading failure mathematical model. The power grid topologies affected by protective relays, circuit breakers and transmission lines are taken into consideration to overcome the disadvantages of complex network theory. The evolution of cascading failures of power system, which is modeled based on the DFT, is significantly closer to the actual physical system behavior. The effectiveness of the proposed risk assessment method is discussed using two test cases.
Abstract: Cascading failure plays an important role in blackouts. Complex network theory, with the disadvantage of ignoring some of physical features of the power systems, is often utilized to model the cascading failure evolution processes. In this paper, a new risk assessment method based on evolution procedure and dynamic fault trees (DFTs), is proposed t...
Show More
-
Impact Performance of W-beam Guardrail Supported by Different Shaped Posts
Tso-Liang Teng,
Cho-Chung Liang,
Ching-Yu Hsu,
Chien-Jong Shih,
Thanh-Tung Tran
Issue:
Volume 4, Issue 2, April 2016
Pages:
59-64
Received:
10 April 2016
Accepted:
Published:
11 April 2016
Abstract: This study applied the finite element code LS-DYNA for evaluating the crashworthiness of W-beam guardrail. Four crash test simulations were conducted for evaluating the safety performance of the W-beam guardrail with four different post configuration according to the European standard EN1317. The results showed that the best performance was demonstrated by the sigma-shaped posts and the I-shaped posts absorbed the lowest amount of impact energy. The optimal result was registered by the barrier with sigma-shaped posts, which demonstrated a lower ASI value and higher energy crash absorption than the other models did.
Abstract: This study applied the finite element code LS-DYNA for evaluating the crashworthiness of W-beam guardrail. Four crash test simulations were conducted for evaluating the safety performance of the W-beam guardrail with four different post configuration according to the European standard EN1317. The results showed that the best performance was demonst...
Show More
-
Analysis of Aeroelastic Stability of Long Straight Wing with Store System
Yan-Ping Xiao,
Yi-Ren Yang
Issue:
Volume 4, Issue 2, April 2016
Pages:
65-70
Received:
17 April 2016
Accepted:
Published:
19 April 2016
Abstract: The aeroelastic equations of long straight wing with store system are developed in this paper by applying the Hamilton’s Principle. The dynamical model takes the store as an independent degree of freedom and considers the geometric nonlinearity of wing. The system dynamics is numerically simulated by using the Galerkin’s method. Results show that the critical flutter speed becomes largest when the store locates at wingtip and around 40% half chord before the elastic axis. The critical flutter speed will decrease as the wing-store joint rigidity decreases. On the other hand, it is shown that sudden change of flutter frequency might occur when the wing-store joint rigidity increases. Moreover, numerical results indicate buckling boundary is independent of store parameters. When the joint rigidity is relatively small, the system flutter occurs first. When the joint rigidity is relatively large, buckling occurs first. With the presence of geometric nonlinearity and increasing flow speed, the system behavior will evolve from limit cycle oscillation, to quasi-periodical motion and eventually to chaos.
Abstract: The aeroelastic equations of long straight wing with store system are developed in this paper by applying the Hamilton’s Principle. The dynamical model takes the store as an independent degree of freedom and considers the geometric nonlinearity of wing. The system dynamics is numerically simulated by using the Galerkin’s method. Results show that t...
Show More
-
Investigating Pitting Corrosion of Stainless Steel and Aluminium Using Scanning Vibrating Electrode Techniques and Electrochemical Noise Measurement
Chinwuba Victor Ossia,
Charles Ugochukwu Orji
Issue:
Volume 4, Issue 2, April 2016
Pages:
71-80
Received:
13 April 2016
Accepted:
22 April 2016
Published:
7 May 2016
Abstract: In this study, the susceptibility of aluminium (Al) and steel SS304 to pitting corrosion in FeCl3 and NaCl solutions with varying pH values were investigated using electrochemical noise (ECN) measurement and Scanning Vibrating Electrode Technique (SVET). Preliminary surface drop test of SS304 in FeCl3 solution and total immersion test of Al in NaCl solution indicated higher pitting of samples at scratches simulated by scribe. Total immersion test on both SS304 and Al indicated that protecting a sample with epoxy-resin mold does not completely eliminate crevice attack. ECN tests results showed that Al suffered severe time-variant corrosion in FeCl3 solution unlike SS304. The results of SVET tests conducted after 24h immersion indicated that the early pits captured on Al samples were more intense than the later ones. Higher corrosion rates were obtained for samples in NaCl solution of pH 2.89 compared to pH 7.21, indicating that pitting increased with acidity. SVET maps obtained corroborated Scanning Electron Microscopy (SEM) images of the sampled surfaces. However, though SVET was unable to capture pitting of SS304 in the solutions, SEM image revealed pitting activity on the sample in FeCl3 solution.
Abstract: In this study, the susceptibility of aluminium (Al) and steel SS304 to pitting corrosion in FeCl3 and NaCl solutions with varying pH values were investigated using electrochemical noise (ECN) measurement and Scanning Vibrating Electrode Technique (SVET). Preliminary surface drop test of SS304 in FeCl3 solution and total immersion test of Al in NaCl...
Show More
-
Label-Free Detection of Aflatoxin B1 Using a Nanomechanical Sensor
Xiarong Zhou,
Shangquan Wu,
Hong Liu,
Xiaoping Wu,
Qingchuan Zhang
Issue:
Volume 4, Issue 2, April 2016
Pages:
81-87
Received:
7 May 2016
Accepted:
Published:
9 May 2016
Abstract: As a highly sensitive nanomechanical sensor, microcantilever sensor is widely used in biochemical detection. Aflatoxin B1 (AFB1), a hepatocarcinogen widely present in food and food materials, is highly dangerous to human health, and new sensitive methods to detect AFB1 are needed. Here, we developed a microcantilever-array-based immunosensor used in stress mode to detect AFB1with the obvious advantages of a high sensitivity, rapidity, label-free, quantitative, and ability to be performed in real-time. The microcantilever was functionalized with a sulfhydrylated anti-AFB1 antibody, and an ELISA was used to validate the activity of the antibody on the microcantilever. Deflection of the microcantilever corresponding to different AFB1 concentrations was monitored in real-time. The detection limit of the microcantilever sensor in stress mode was lowered to 0.03 ng/mL for AFB1, which is a significant improvement in comparison with icELISA or a microcantilever sensor operated in dynamic mode. We also successfully detected AFB1 dissolved in a peanut solution. The microcantilever sensor in stress mode provides a new method for detecting extremely low concentrations of AFB1 and may have great potential for food quality control and public health protection.
Abstract: As a highly sensitive nanomechanical sensor, microcantilever sensor is widely used in biochemical detection. Aflatoxin B1 (AFB1), a hepatocarcinogen widely present in food and food materials, is highly dangerous to human health, and new sensitive methods to detect AFB1 are needed. Here, we developed a microcantilever-array-based immunosensor used i...
Show More
-
Modeling and Optimization of Hard Turning Operation on 41Cr4 Alloy Steel Using Response Surface Methodology
Christopher Okechukwu Izelu,
Samuel Chikezie Eze,
Festus Ifeanyi Ashiedu
Issue:
Volume 4, Issue 2, April 2016
Pages:
88-102
Received:
3 May 2016
Accepted:
14 May 2016
Published:
30 May 2016
Abstract: Product quality, productivity and organizational goodwill are often the major concern of every production or manufacturing unit. These criteria, more especially product quality, cannot readily and effectively be met through dependence on the skills of an operator. Hence, the need for optimization in order to identify the best process condition, derived from parametric combinations of process variables, for the manufacturing process. The work presented concerns an aspect of a series of hard turning experiments on 41Cr4 alloy structural steel conducted to model, predict and optimize the machining induced vibration, and the surface roughness as functions of the cutting speed, feed rate, and the tool nose radius. The response surface methodology, based on the central composite design of experiment is employed in the study, and analysis of the generated data performed with the aid of Design expert 9 software. A quadratic regression model was suggested as best fits for both the machining induced vibration and surface roughness data. These were confirmed by analyses of variance, which also revealed the tool nose radius and cutting speed, as well as the feed rate and cutting speed to be important factors that determine changes in the machining induced vibration and surface roughness, respectively. The optimum setting of the tool nose radius at 1.72301 mm, feed rate at 0.15 mm/rev, and the cutting speed at 311.075 rev/min minimized the machining induced vibration to a value of 0.08 mm/min2 and the surface roughness to a value of 4.74 µmm.
Abstract: Product quality, productivity and organizational goodwill are often the major concern of every production or manufacturing unit. These criteria, more especially product quality, cannot readily and effectively be met through dependence on the skills of an operator. Hence, the need for optimization in order to identify the best process condition, der...
Show More
