Important Engineering Task Research Articles

A PACVD duplex coating for hot-forging applications

The tribological loading of forging tools is caused by the relative motion between the plastically deformed work piece and the die. In comparison to many other forming processes, hot forging has an especially disadvantageous tribological system, combining thermal, mechanical and chemical loadings. The advantages of hard coatings, which are well known for cutting tools, are to a much lesser extent explored for casting, extrusion, moulding and forging tools. Increasing the lifetime of these tools is an important task in surface engineering because of the complex loading conditions and the often complicated tool geometry, with the plasma-assisted chemical vapour deposition (PACVD) technique being well suited to the depositing of hard coatings onto large dies and moulds. The aim of this paper is to present and discuss possible improvements to industrial applications (i.e., the hot forging of automotive parts) obtained by the duplex PACVD coating of forging dies. The experimental results indicate that the deposition of a proper duplex PACVD coating and the use of a proper substrate treatment lead to improved tribological properties and a longer lifetime for the hot-forging die.

진동 파워흐름 측정을 통한 SUV용 엔진 마운트의 에너지 전달 기여도 분석에 관한 연구

Reduction of structure-borne noise in the compartment of a car is an important task in automotive engineering. Many methods which analyze noise transfer path have been generally used for structure-borne noise. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation for each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow measurement has been used for a simple isolation system or a laboratory based isolation system. This paper identifies the transfer path of booming noise in a SUV. The powertrain used for test has a in-line 4cylinder engine and 5-shift auto-transmission. This powertrain is transversely supported by four isolators. We calculated the energy flow throughout four isolator by the measurement of power flow and the contribution of energy flow at each isolator.

Prediction of Lateral Effective Stresses in Sand using Artificial Neural Network

Predicting the lateral effective stress and the coefficient of lateral earth pressure at rest values is an important task in geotechnical engineering since it is used in the design and analysis of earth retaining structures, slope stability, piles and pier foundations. It needs sophisticated test procedures. The laboratory and in situ tests are also expensive and time consuming. In this study, an artificial neural network model is developed to predict the σ h , lateral effective stress in cohesionless soils. Back propagation neural networks are used for function approximation and model has been trained by Levenberg-Marqurdt (LM) learning algorithm. The data used in the running of network models have been obtained from extensive series of oedometer tests on Kilyos, Ayvalik and Yalikoy sands. Tests were carried out on loose, medium dense and dense state of compactness in normal loading, unloading and reloading conditions. The test results demonstrate that there is a linear relationship between vertical and lateral stresses for normally loaded cohesionless soils under K 0 conditions. K 0 values obtained for the loose state of compactness are higher than for the dense state of compactness. The results of the artificial neural network model indicate that the model serves as simple and reliable tool to predict σ h and also K 0 in cohesionless soils. The variation of K 0 values with internal friction angles is obtained and a simple expression is derived from this relationship.

Three-dimensional numerical analysis of stress and deformation of surrounding soil in safety construction of metro station

Utilizing underground spaces synthetically has become an important task in urban planning and civil engineering in this century. Due to the complexity and uncertainty of technical issues in underground construction and soil engineering, construction safety arouses a great concern in underground construction industry. This paper focused on construction of an underground metro station, numerical analyses are carried out to estimate the possible stresses and deformations of surrounding soil and underground structures under the worse loading conditions to assess the structural design and construction safety. Influences of pit excavation on existing tunnel and surrounding spaces are discussed and the stability of main structure of metro station will be analyzed.

Support vector machine applied to settlement of shallow foundations on cohesionless soils

The determination of settlement of shallow foundations on cohesionless soil is an important task in geotechnical engineering. Available methods for the determination of settlement are not reliable. In this study, the support vector machine (SVM), a novel type of learning algorithm based on statistical theory, has been used to predict the settlement of shallow foundations on cohesionless soil. SVM uses a regression technique by introducing an ε – insensitive loss function. A thorough sensitive analysis has been made to ascertain which parameters are having maximum influence on settlement. The study shows that SVM has the potential to be a useful and practical tool for prediction of settlement of shallow foundation on cohesionless soil.

Shape‐engineered fibroblasts: Cell elasticity and actin cytoskeletal features characterized by fluorescence and atomic force microscopy

The regulation of cell shape, which determines cell behaviors including adhesion, spreading, migration, and proliferation in an engineered artificial extracellular milieu, is an important task in tissue engineering and in development of functional biomaterials. To deepen the understandings of shape-dependent cell mechanics, the cell elasticity and structural features of the actin cytoskeleton (CSK) were characterized for shape-engineered fibroblasts; round and spindle-shaped cells cultured on photolithographically microprocessed surfaces, employing the cellular microindentation tests and fluorescence observation of actin CSK by the combination of atomic force microscopy (AFM) and fluorescence microscopy (FM). The relationships among cell elasticity, the structural features of actin CSK, and engineered cell shape were analyzed and compared with those of control cells that had been cultured on nonprocessed surfaces (termed naturally extended cells). Results showed that the spindle-shaped cells with sparse or no apical stress fibers (ASFs) exhibited similar stiffness to that of the naturally extended cells with dense ASFs. The elasticity of spindle-shaped cells was affected only slightly by the stress fiber (SF) density, which is in marked contrast to the significant correlation shown between cell elasticity and SF density in naturally extended cells. This result implies that the elasticity of regionally restricted adhesion-surface-induced shape-engineered cells, particularly of highly elongated cells, is affected predominantly by cell shape rather than by structural features of SFs.

Simulation-based approach for the accurate fabrication of blazed grating structures by FIB

Accurate direct fabrication of diffractive gratings is an important task in optical engineering. Several methods have been reported to realize optical diffractive gratings on a silicon substrate using focused ion beams. A method, however, is necessary to improve the overall shape and dimensional accuracy. In this paper a simulation-based technique is presented taking into account redeposition fluxes. First, the influence of the process parameters on the blazed grating structure is studied experimentally. Then the process parameters for a structure with a planar sidewall, a maximum depth of 200 nm, and an opening width of 350 nm are determined. The approach is finally verified by comparing the designed with the fabricated structure. The method may be readily extended to various micro/nano structures in optics.

Progress towards tubes with regular nanopatterned inner surfaces

The repair of vascular tubing is an important task in tissue engineering. The behavior of cells is strongly influenced by the topology of the surfaces, on both a micrometric and a nanometric scale, in their vicinity. Thus the authors wish to make tubes that are patterned on the inner surface. One way to do this is to use the good depth of focus capabilities of x-ray exposure to print an array of dots, 200nm diameter and 400nm pitch, onto a curved surface coated in resist. A die made from this structure allows nanoembossing into a biodegradable polymer. A closed vessel can then be made by adding a lid, that also has a similar nanopatterned surface. Details of the accuracy of transfer are given. It is concluded that x-ray printing is a suitable approach for the formation of internally patterned tubing.

The Analytic Hierarchy Process: A Tutorial for Use in Prioritizing Forest Road Investments to Minimize Environmental Effects

The prioritization of road maintenance projects is an important forest engineering task due to limited budgets and competing investment needs. Large investments are made each year to maintain and upgrade forest road networks to meet economic and environmental goals. Many models and guidelines are available for single-criteria analysis of forest roads, however we have found no method for multi-criteria analysis. Additionally, even single criteria approaches often rely on expert judgment to inform models of user preferences and priorities. These preferences are used to make tradeoffs between alternatives that contain data that are physical and biological, quantitative and qualitative, and measured on many different scales. The Analytic Hierarchy Process (AHP) has the potential to provide a consistent approach to the ranking of forest road investments based on multiple criteria. AHP was specifically developed to provide a consistent, quantifiable approach to problems involving multi-criteria analysis, but it has not been applied to road management. AHP is composed of four steps: the hierarchical decomposition of a problem into a goal, objectives, and sub-objectives; the use of a pairwise comparison technique to determine user preferences; the scaling of attribute values for each of the alternatives; and the ranking of alternatives. The road investment problem differs from traditional AHP applications in that potentially thousands of alternatives are compared at one time. We discuss the AHP methodology including the foundations, assumptions, and potential for use in prioritizing forest road investments to meet economic and environmental goals, drawing from an example from the Oregon State University College Forests.

Reuse of Fly Ash-Amended Petroleum-Contaminated Soils in Highway Embankments

Remediation of contaminated soil and groundwater has been an important task for engineers and scientists in recent years. One of the sources of soil and groundwater contamination in the United States is petroleum spills. A laboratory study evaluated the geotechnical engineering properties and environmental suitability of remediated petroleum-contaminated soils for their possible use in highway construction. The laboratory test program included compaction, batch sorption, and long-term column leaching tests. Diesel fuel, naphthalene, and a model nonaqueous phase liquid (NAPL) were used as the pollutants; waste coal fly ash that included high carbon content was used to stabilize the contaminated soils. Compaction test results indicated that the maximum unit weights and optimum liquid contents of the stabilized soils satisfy the limits set for highway embankment construction. The results of the batch-scale adsorption tests conducted on the fly ash revealed that the ash has good naphthalene sorption propertie...

Reuse of Fly Ash–Amended Petroleum-Contaminated Soils in Highway Embankments

Remediation of contaminated soil and groundwater has been an important task for engineers and scientists in recent years. One of the sources of soil and groundwater contamination in the United States is petroleum spills. A laboratory study evaluated the geotechnical engineering properties and environmental suitability of remediated petroleum-contaminated soils for their possible use in highway construction. The laboratory test program included compaction, batch sorption, and long-term column leaching tests. Diesel fuel, naphthalene, and a model nonaqueous phase liquid (NAPL) were used as the pollutants; waste coal fly ash that included high carbon content was used to stabilize the contaminated soils. Compaction test results indicated that the maximum unit weights and optimum liquid contents of the stabilized soils satisfy the limits set for highway embankment construction. The results of the batch-scale adsorption tests conducted on the fly ash revealed that the ash has good naphthalene sorption properties because of the presence of high carbon content in its structure. Column leaching test results suggested that the naphthalene and o-xylene concentrations in the effluents collected from the fly ash–stabilized specimens were lower than those collected from the control specimens (i.e., borrow material). The findings indicate that the high carbon content fly ashes can be good sorptive agents for remediation of petroleum contaminated soils because of their low cost and presence of high carbon content. However, caution should be exercised when the laboratory results are carried to field conditions, because the level of contamination is likely to influence the leaching properties.

Equilibrium of Lane Flow Distribution on Motorways

The distribution of traffic flow in the individual lanes of multilane motorways is an important investigation task in traffic engineering, because the lane flow distribution directly affects the capacity of the motorway section under investigation. Following the basic idea of the work of Heidemann, the flow distribution in the individual lanes was rederived and extended to carriageways with more than three lanes. The model was then calibrated with field data obtained from Germany. In addition, the proposed model was extended to congested traffic conditions. The proposed model can therefore be applied for entire flow conditions in reality.

Equilibrium of Lane Flow Distribution on Motorways

The distribution of traffic flow in the individual lanes of multilane motorways is an important investigation task in traffic engineering, because the lane flow distribution directly affects the capacity of the motorway section under investigation. Following the basic idea of the work of Heidemann, the flow distribution in the individual lanes was rederived and extended to carriageways with more than three lanes. The model was then calibrated with field data obtained from Germany. In addition, the proposed model was extended to congested traffic conditions. The proposed model can therefore be applied for entire flow conditions in reality.

Reduction of welding deformation by the twin beams method. A study of deformation behaviour due to laser welding of automotive parts at micron or submicron level

Amid growing concern over the global environment, manufacture of environmentally friendly automotive parts that provide cleaner exhaust gas emissions and improved fuel efficiency is seen as an important engineering task. To develop automotive parts which meet these requirements, it is necessary to achieve a processing accuracy in a range of several microns to submicron level. Production technology in welding and joining, including laser processing, has also been intensively researched from this perspective. Figure 1 gives typical examples of the accuracy requirements extending to specific automotive parts.

Iso-phote based adaptive surface fitting to digitized points and its applications in region-based tool path generation, slicing and surface triangulation

An important task in computer graphics, computer-aided design and reverse engineering is the mathematical modeling of three-dimension complex surfaces based on digitized points. However, there are several open problems that are viewed as a bottleneck in the mathematical modeling. The topology is unknown. The reconstruction is based on parameterization and fitting stages. The above problems are influenced mainly by the parameterization, and the issue of parameterization for curve and surface fitting has been a difficult one since the advent of computers in design engineering. To resolve the above problems, in this paper a new strategy based on region-by-region adaptation is presented to surfaces fitting for digitized points. Furthermore, the “regions” used for adaptive surface fitting can be applied extendedly to three industrial applications: (1) tool path generation; (2) slicing; and (3) surface triangulation.

Reciprocal interactions between cells and extracellular matrix during remodeling of tissue constructs

Cells remodel extracellular matrix during tissue development and wound healing. Similar processes occur when cells compress and stiffen collagen gels. An important task for cell biologists, biophysicists, and tissue engineers is to guide these remodeling processes to produce tissue constructs that mimic the structure and mechanical properties of natural tissues. This requires an understanding of the mechanisms by which this remodeling occurs. Quantitative measurements of the contractile force developed by cells and the extent of compression and stiffening of the matrix describe the results of the remodeling processes. Not only do forces exerted by cells influence the structure of the matrix but also external forces exerted on the matrix can modulate the structure and orientation of the cells. The mechanisms of these processes remain largely unknown, but recent studies of the regulation of myosin-dependent contractile force and of cell protrusion driven by actin polymerization provide clues about the regulation of cellular functions during remodeling.

On the selection of variables for qualitative modelling of dynamical systems

Behavioural modelling of physical systems from observations of their input/output behaviour is an important task in engineering. Such models are needed for fault monitoring as well as intelligent control of these systems. The paper addresses one subtask of behavioural modelling, namely the selection of input variables to be used in predicting the behaviour of an output variable. A technique that is well suited for qualitative behavioural modelling and simulation of physical systems is Fuzzy Inductive Reasoning (FIR), a methodology based on General System Theory. Yet, the FIR modelling methodology is of exponential computational complexity, and therefore, it may be useful to consider other approaches as booster techniques for FIR. Different variable selection algorithms: the method of the unreconstructed variance for the best reconstruction, methods based on regression coefficients (OLS, PCR and PLS) and other methods as Multiple Correlation Coefficients (MCC), Principal Components Analysis (PCA) and Cluster analysis are discussed and compared to each other for use in predicting the behaviour of a steam generator. The different variable selection algorithms previously named are then used as booster techniques for FIR. Some of the used linear techniques have been found to be non-effective in the task of selecting variables in order to compute a posterior FIR model. Methods based on clustering seem particularly well suited for pre-selecting subsets of variables to be used in a FIR modelling and simulation effort.

A Freeform Surface Modelling System Based on Laser Scan Data for Reverse Engineering

Reverse engineering technology starts with a measurement process, inspecting the surface contour of the object, and applies a CAD geometric modelling technique to construct the surface model. The purpose of this study is to develop a freeform surface modelling system involving the functions of data reorganisation and surface construction of reverse engineering. An important task in reverse engineering is the process of reducing the large amount of coordinate data derived by measurement devices. Reduction methods in common use include uniform deviation, division by a factor, spatial sampling, chordal deviation and interpolated sampling. Each of the above modes has its advantages and weaknesses, and suitable application areas. A new data reduction mode, which integrates the space concept and height characteristic, is proposed, called the height decision method. This method can achieve the aim of data simplification while maintaining the curve characteristics of the model. The CAD modelling system is developed by an AutoLISP program with MDT v4.0 software. An egg model is presented in this paper for explanation and verification.

Application of Vibrational Power Flow to a Passenger Car for Reduction of Interior Noise

Reduction of structure-borne noise in the compartment of a car is an important task in automotive engineering. Transfer path analysis using the vibroacoustic reciprocity technique or multiple path decomposition method has generally been used for structure-borne noise path analysis. These methods are useful for solving a particular problem, but they do not quantify the effectiveness of vibration isolation of each isolator of a vehicle. To quantify the effectiveness of vibration isolation, vibrational power flow has been used for a simple isolation system or a laboratory-based isolation system. It is often difficult to apply the vibrational power flow technique to a complex isolation system like a car. In this paper, a simple equation is derived for calculation of the vibrational power flow of an isolation system with multiple isolators such as a car. It is successfully applied not only to quantifying the relative contributions of eighteen isolators, but also to reducing the structure-borne noise of a passenger car. According to the results, the main contributor of the eighteen isolators is the rear roll mount of an engine. The reduced structure-borne noise level is about 5dBA.

From university term papers to industry technical reports — An attempt to bridge the existing gap

The authors investigate the reasons for the existing university-industry written communication gap and suggest ways for bridging it. Most university programs do not adequately help students with technical communications. Consequently, the new engineer, when hired, will have the burden of overcoming the gap of technical writing apart from other important engineering tasks. Industry and university should cooperate in helping new engineers with this important facet of their careers. A first action could be to supplement the college-level curriculum with courses on technical writing, documentation, editing, and the use of new communication systems based on real industry requirements. These courses, which could be continued in industry in the form of seminars, help from senior peers, and the publication department, along with personal efforts, would enable young engineers to comprehend the basic principles that help in writing effective reports and proposals in the real engineering world.