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When the fine-blanking process is used, secondary grinding or processing can be omitted because the shear surface of fine-blanking parts can achieve almost zero fracture zone requirements. Fine-blanking has the advantages of high precision and high production efficiency. It was originally used on watch parts, but with increasingly refined technology, it has been widely applied in computers, consumer electronics, communication products, and vehicle parts. The primary objective of the fine-blanking process is to reduce the fracture zone depth and die roll zone width. This study used a 2.5mm thick central processing unit (CPU) thermal heat spreader as an example. Finite element analysis software was employed to simulate and optimize the main eight process parameters that affect the fracture zone depth and die roll zone width after fine-blanking: the V-ring shape angle, V-ring height of the blank holder, V-ring height of the cavity, V-ring position, blank holder force, counter punch force, die clearance, and blanking velocity. Simulation analysis was conducted using the L18 (21×37) Taguchi orthogonal array experimental combination. The simulation results of the fracture zone depth and die roll zone width were optimized and analyzed as quality objectives using Taguchi’s smaller-the-better design. The analysis results revealed that with fracture zone depth as the quality objective, 0.164 mm was the optimal value, and counter punch force made the largest contribution of 25.89%. In addition, with die roll zone width as the quality objective, the optimal value was 1.274 mm, and V-ring height of the cavity made the largest contribution of 29.45%. Subsequently, this study selected fracture zone depth and die roll zone width as multi-criteria quality objectives and used the robust multi-criteria optimal approach and Pareto-optimal solutions to perform multi-criteria optimization analysis. The results revealed the optimal fracture zone depth and die roll zone width were 0.239 mm and 1.288 mm, respectively. Finally, the experimental results verified that the fracture zone depth was 0.230 mm and die roll zone width was 1.205 mm. The findings met the industry’s fraction zone depth standard (below 12% of blank thickness) and achieved a smaller die roll zone width.

The introduction of the servo press in recent years has opened up options for metal stamping; within this context, enhancing material formability and reducing stamping time are important goals. Focusing on a case study of rectangular cup stamping, this study optimized the pulsating curve for a servo press. First, the forming depths, thinning ratios, and forming time resulting from a pulsating curve and a crank curve were compared. Experiment results indicated that the pulsating curve could produce 92.3 % greater forming depth and an 8% smaller thinning ratio at the same forming depth as the crank curve. Next, finite element software was used to optimize the lifting velocity, press-in velocity, lifting distance, and press-in distance of the pulsating curve with forming time, thinning ratio, and forming force as single objectives. For single-objective optimization, the smaller-the-better formula of the Taguchi method was used and the analysis values of the optimal parameter combinations were compared with the optimal analysis values of nine analysis. The optimal parameter combinations produced a shorter forming time (0.06 s less), a lower thinning ratio lower (0.1425 % less), and a smaller forming force (808 N smaller). Using ANOVA and multiple regression analysis, the influence of the four process parameters on the quality characteristics and derived their mathematical relationships were calculated and their mathematical relationships derived. Next, with forming time, thinning ratio, and forming force as the quality objectives, multi-objective optimization was conducted using the Taguchi method. The grey-entropy method, and grey relational analysis were also used. Experimental verification results revealed that the grey relational grade of the optimal parameter combination was higher than those of the nine analysis. Furthermore, lifting velocity exerted the greatest influence on the multiple quality characteristics with a contribution of 55.01 %.

In recent years, metal components produced through die forming have decreased in size leading to challenges in drawing forming. In this study, an optimal microridge punch was designed using the robust multi-objective design in the fuzzy Taguchi method to enhance the formability of deep drawing process. Using a round, stainless steel cup measuring 2.5 mm in inner diameter and 0.1 mm in thickness, four punch microridge dimension parameters that influenced the thinning rate (TR) and stripping force (SF) during drawing forming were explored. The design performances of two objective functions, namely, the TR and SF, were assessed using the Taguchi method. The effect of the design parameters on the objective functions were verified using a factor effect analysis and an analysis of variance (ANOVA), whereas the measuring index of optimal multiple performance characteristics (MPC) was obtained using fuzzy logic inference. The analysis results showed that the dimension parameters that influenced TR and SF contribution, listed in descending order, were ridge gap (45.25%), ridge nose radius (40.86%), ridge-to-nose distance (11.18%), and ridge height (2.71%). The optimal values were subsequently used to design and produce drawing dies and an experiment was performed to verify their effectiveness. The experiment result showed that the optimal ridge punch drawing distance reached 1.542 mm, which was an increase of 55.60% compared with the drawing distance of non-ridge punch (0.993 mm).

This research is aimed toward an understanding of the effects of the chemical characteristics and mineral compositions of sandstone and formation water based on saline water-rock-supercritical CO2 interaction simulation experiments. These experiments were conducted to assess whether toxic trace elements could be dissolved and released in formation water from sandstone in a CO2 storage layer after CO2 geological sequestration, thus affecting groundwater quality. The experimental results reveal that the concentrations of Cd and Pb in the water under examination exceeded the national primary drinking standard as a result of saline/fresh water-rock-supercritical CO2 interactions after 40 d of sandstone immersion in saline/fresh water and 20 d of interaction. In addition, the Mn concentration in the saline/fresh water exceeded the national secondary drinking standard after 40 d of sandstone immersion and 20–80 d of interaction. However, Cd, Pb, and Mn were released to a greater extent (in terms of concentration, 2-fold for Cd, 7-fold for Pb, and 1.7-fold for Mn) in the presence of salinity, revealing that salinity may enhance the dissolution of Cd, Pb, and Mn after 20 d of saline water-rock-scCO2 interaction. After a long period of supercritical CO2-sandstone interaction, the trace metals previously mobilized can be immobilized again by an increase in alkalinity due to aragonite dissolution.

Excess carbon dioxide emission was considered as the most important cause of increased trend of global warming. Significant amounts of research were devoted to the reduction of CO2 emission and CO2 sequestration. Sequestration of CO2 in empty oil reservoirs was considered as one of the most promising options. However, the effects of metal release and mobility as a result of CO2 injection were not studied in detail, particularly under super-critical CO2 (scCO2) conditions. In this study, the release of selected metals immersed in distilled water for varying amounts of time in the absence and presence of scCO2 was assessed in simulated conditions at 90°C and 24 MPa. Significant increases in dissolution of Fe, Sr, and Ba by 3, 8, and 24 times were found when the storage rock sandstone or caprock shale was immersed in DI water for different time period. However, in the presence of scCO2, the dissolution of these metals was reduced by 80% for Fe, suggesting permanent sequestration of scCO2 into carbonate minerals. The trend in changes of pore water chemistry in the sandstone and shale after being immersed in DI water showed dissolution of Sr-bearing mineral and precipitation of Ba-bearing mineral.

Because of product miniaturization, demand for cups created by deep drawing has increased. However, because thin sheet materials exhibit poor deep drawing formability, using deep drawing on micro/meso cups is rather difficult. In this study, punch surfaces with microridges were used to enhance deep drawing formability. The concept was based on the observation that punch surfaces with microridges near the punch nose could disperse the drawing force of punches on sheet materials and delay the cracking of sheet materials. In this study, cylindrical cups composed of copper alloy were used. First, punch surfaces with microridges were designed and the Deform 2D software was used for analyzing the formability of deep drawing by using punch surfaces with and without microridges. Second, drawing dies were designed and produced, and an experiment was conducted to verify the results of the analysis. The study results indicated that commercial forming analysis software can be used to simulate the effect of microridges on deep drawability accurately. A comparison between the two punch surface types revealed that punch surfaces with microridges exhibited a slightly increased drawing force (3%) compared with those without microridges. Concurrently, the effect of punch surfaces with microridges increased forming height by at least 100%.

In this study, the influence of indium tin oxide (ITO) top electrodes with different oxygen contents on the resistive switching characteristics of HfO x /TiN capacitor structure is investigated. Switching parameters, including set and reset voltage values, and high and low resistance values are highly related to the properties of ITO thin films. Higher resistance values in both states can be obtained when ITO thin films with higher oxygen contents are used as top electrodes; such values are accompanied by larger set voltages and fluctuating transient currents during the reset process. Based on the proposed filament model, we suggest that the switching mechanism of HfO x /TiN structure is attributed to the formation and rupture of conducting filamentary paths near the anodic side, which is highly correlated with the properties of the top electrode. The top electrode must be well determined to obtain reliable switching properties.

Springback will occur when the external force is removed after bending process in sheet metal forming. This paper proposed an adaptive-network-based fuzzy inference system (ANFIS) model for prediction the springback angle of the SPCC material after U-bending. Three parameters were selected as the main factors of affecting the springback after bending, including the die clearance, the punch radius, and the die radius. The training data were obtained from results of U-bending experiment. The training data with four different membership functions – triangular, trapezoidal, bell, and Gaussian functions –were employed in the ANFIS to construct a predictive model for the springback of the U-bending. After the comparison of the predicted value with the checking data, we found that the triangular membership function has the best accuracy, which make it the best function to predict the springback angle of sheet metals after U-bending.

A transparent resistive random access memory used as Indium Tin Oxide (ITO) electrode, ITO/HfO2/Al2O3/…/HfO2/Al2O3/ITO capacitor structure is fabricated on glass substrate by atomic layer deposition. The unipolar resistive switching characteristics can be performed by applying the positive- or negative-bias through top electrode, however, the differences of switching and stability in the two different operations can be observed. The diversities of electrical property are attributed to different oxide/ITO interface materials, which influence the current flow of the injected electrons.

Previous researchers have investigated anti-plane problems of a crack terminating at an interface within an infinite domain. This study is devoted to the theoretical analysis of these crack terminating problems for a circular composite material with a finite radius. Detailed solutions for a composite with a crack terminating at the interface under anti-plane loading were derived by employing a double transform that consists of the finite Mellin and Laplace transforms. Using the proposed method, related problems of anti-plane shearing can be solved in a straightforward manner. According to these solutions, stress intensity factors are obtained and discussed. Based on the problems studied with the maximum shear stress criterion, the crack may be interfacial debonded or may penetrate through the interface, but it cannot be reflected back.

A transparent resistive random access memory based on ITO/Gd"2O"3/ITO capacitor structure is fabricated on glass substrate. The transparent memory exhibits reliable resistive switching for more than 1000 cycles, low operation voltage of -2V/+2V, and highly transmittance above 80% for visible light. From the TEM and XPS analysis, the asymmetry of the interfacial layer thickness is responsible for the asymmetric switching properties. The transitional multi-valance states of the bottom interfacial layer can serve as oxygen reservoir for oxygen migration back and forth under different polarity of applied bias. This work presents a candidate material Gd"2O"3 for the application on the T-RRAM devices.

Springback is a primary issue which is encountered during most sheet metal bending processes. Using the Taguchi method, this study investigates the springback of L-bending with a step in the die through simulation and experiments for AZ31 magnesium alloy sheets at different temperatures. The process parameters for bending springback in this study include: lower punch radius, die clearance, step height, and step distance; we use a Taguchi L9 orthogonal array to design the combinations for the experiments. The results of ANOVA analysis show that, for each bending temperature, the process parameters that affect springback occur in the following order: step height (greatest), lower punch radius (next), die clearance (smaller), and step distance (smallest). In addition, with the increase of the bending temperature, the angle of springback decreases. The optimal parameter combinations at each bending temperature from the signal-to-noise response are all the same, namely, a die radius of 2 mm, die clearance of 0.5 mm, step height of 0.1 mm, and step distance of 2 mm. When the bending temperatures are 100°C, 150°C, and 200°C, the angles after springback of the optimal experimental parameter combination are 91.06°, 90.63°, and 89.84°, respectively.

The resistive switching (RS) behavior of the Ti/Gd2O3/Pt capacitor structure is fabricated and discussed in this paper. The switching characteristics operated under positive bias exhibits stable switching properties with a condensed voltage and resistance values dispersion, while the switching characteristics becomes unstable and large fluctuation on switching parameters under the negative bias operation. We suggest that the anode electrode plays an important role to the switching characteristics, and might be the causes of the asymmetry of the I-V curves between positive and negative operation. Constant voltage stress measurement is also tested to reveal the switching mechanism of the Gd2O3 film, and the switching mechanism is mainly based on the applied voltage and thermal Joule heat.

In the sheet metal stamping process for automobiles, the drawing process requires the greatest stamping force, and thus the structure of the drawing dies is the thickest and heaviest among all stamping dies. This study describes how the fuzzy-based Taguchi method can be applied to explore multi-objective optimization in the structural design of drawing dies. Using the lower die of the drawing die for the engine hood’s outer panel as an example, the current study explores four parameters that primarily influence the strength and weight of their structure, namely the rib thickness of the punch open line, the pitch of the structure rib, the thickness of the punch surface, and the thickness of the structure rib. Firstly, CATIA software is used to construct a geometric model of the drawing die, and a structural analysis of the model is performed. Next, within the constraints of allowable stress, allowable deflection and allowable size and pitch of the rib, etc., we apply the Taguchi method to evaluate the allowable characteristics of the two objective functions, namely the deflection and weight of the lower die. Then, through factor effect analysis and analysis of variance, the influences of the design parameters upon the objective functions are determined. Next, a fuzzy logic inference is utilized to obtain the measuring index which results in the optimization of the multiple performance characteristics. Finally, by comparing the results from the maximized design and the results from the original design, it is shown that the deflection of the lower die structure is only increased by 0.0038 mm (8.1%), but its weight can be greatly decreased by 506 kg (12%).

This paper studies the effect of ultraviolet (UV) light exposure on the resistive switching characteristics of an ITO/HfO x /TiN structure. Unstable and unreliable switching properties are generally observed on the ITO/HfO x /TiN sample. Under the appropriate exposure time, the samples were able to achieve the superior electrical characteristics and reduced resistance dispersion. We suggest that the improvement of switching characteristics and resistance dispersion is related to the oxygen-rich HfO 2 layer formed at the M/O interface caused by UV light. This indicates that UV laser exposure is a critical issue in the electrical characteristics of RRAM devices.

Magnesium alloys are becoming more and more popular because of their high specific strength, light specific weight, recyclability, and ability to shield electromagnetic shocks. This paper introduces an integrated RE/RP/CAD/CAE/CAM system for constructing a magnesium-alloy AZ31 shell for the mobile phone and developing related progressive dies using concurrent engineering (CE). This integrated system uses an optical scanning system (ATOS), a rapid prototyping machine (SOUP600), a CAD/CAE/CAM software (CATIA), a sheet metal forming simulation software (DYNAFORM), a CAM software (POWERMILL), and a die design knowledge-based system as the operating platform. The die design knowledge-based system includes die design procedures, die design standards, design criteria, and empirical formulae. Our system has been used successfully in constructing a magnesium-alloy AZ31 shell for the mobile phone and developing related progressive die. Since the entire development process shares the same 3D geometric model, the various process of developing dies can be performed in parallel. Our system can greatly reduce the development time and cost, improve the product quality, and push products into the market in a relatively short time.

The globalization and competition in the automobile industry makes it necessary to reduce the time spent on product development. Therefore, computer aided product development has become one of the most important techniques in the automobile industry. According to the concurrent engineering concept, an integrated CAD/CAE/CAM system for automobile stamping die development is established. The system is based on 3D surface construction CAD software STRIM, CAD/CAE software CATIA, stamping formability analysis software DYNAFORM, CAM software CADCEUS, a stamping design knowledge-based system, and a product database. This paper uses the development of trunk lid outer panels as an example to showcase the power of the system, in which the different development stages can be performed simultaneously. The system can greatly reduce the development time and cost, improve the product quality, and push products into the market in a relatively short time.

A novel time-domain approach is proposed to synthesize the broadband macro-pi model of the differential vias based on time-domain reflected/transmitted waveforms either measured by time-domain reflectometry (TDR) or simulated by finite-difference time-domain (FDTD) method. The step responses of the differential via are solved in terms of rational functions by the generalized pencil-of-matrix (GPOM) method. The macro-pi model in terms of the rational functions pairs is obtained through an ABCD matrix transformation. The order of the macro-pi model can be reduced without losing the accuracy according to a residue criterion. The equivalent lumped circuits of the macro-pi model is synthesized by a lumped circuit extraction method (LCEM). The stability and passivity of the extracted models can be preserved based on this time-domain approach and the macro-pi topology. Two examples, one is an asymmentric via and the other is an differential via in four-layer PCB, are used to demonstrate the broadband accuracy of the proposed approach both in time-domain and frequency-domain

Based on a novel multidimensional deconvolution algorithm (MDA), this paper proposes a time-domain approach to synthesize the broadband SPICE-compatible macromodels of coupled interconnects. The multiple conductor interconnects are excited either experimentally by TDR or numerically by the step-like source in finite difference time domain (FDTD) method. According to the time-domain scattered data, the macromodel of the interconnect can be efficiently extracted by cascading several configuration-oriented coupled transmission lines (CCTL). Two examples are used to demonstrate the validity of the proposed approach. One is the equivalent models for differential pairs crossing an asymmetrical ground slot. The other is the crosstalk behavior prediction for a three-coupled microstrip line. The accuracy in broadband frequency range of the synthesized models of these two examples are checked both in time and frequency domain and compared with the direct-FDTD simulation. The agreement is favorably good.

Based on time-domain scattered data, an efficient systematic approach in the time domain has been proposed to extract the SPICE-compatible models of embedded high-speed interconnects. The approach combines the layer-peeling technique and the generalized pencil-of-matrix method to obtain a pole-residue representation of the step response of the interconnects. An order-reduction procedure is implemented based on the bandwidth criterion to find the optimum pole-residue representation of the interconnects with minimum pole numbers. The SPICE-compatible lumped circuits are then systematically extracted from the pole-residue rational functions. The discontinuous microstrip lines and bonding wire structure are used to demonstrate the validity of the proposed approach. Good agreement is seen between the modeled and measured transient response. The advantages of this approach are the de-embedding ability for arbitrary nonuniform interconnects, systematically obtaining lower order and more accurate SPICE-compatible circuits, and broad-band performance of the extracted circuits.

The influence of a nonionic surfactant (Triton X-100) on the contaminant distribution coefficients in solid-water mixtures was determined for a number of relatively nonpolar compounds (contaminants) on several natural solids. The studied compounds consisted of BTEX (benzene, toluene, ethylbenzene, and p-xylene) and chlorinated pesticides (lindane, alpha-BHC, and heptachlor epoxide), which span several orders of magnitude in water solubility (S(w)); the solid samples comprised a bentonite, a peat, and two other soils, which cover a wide range of solid organic matter (SOM) content. The applied surfactant concentrations (X) ranged from below the (nominal) CMC to 2-3 times the CMC. For relatively water-soluble BTEX compounds, the distribution coefficients with surfactant (K(d)*) all exceeded those without surfactant (K(d)); the K(d)*/K(d) ratios increased with increasing S(w) from p-xylene to benzene on each solid at a given X, with increasing X for each compound on a solid, and with decreasing solid SOM content for each compound over the range of X studied. For the less-soluble pesticides, the K(d)*/K(d) ratios exhibited a large increase with X for bentonite, a marginal change (increase or decrease) for a soil of 2.4% SOM, and a moderate-to-large decrease for two soils of 14.8% and 86.4% SOM. These unique observations were rationalized in terms of the properties of the compound, the amount of surfactant sorbed on the solid, the enhanced solubilization of the compound by surfactant in water, and the relative effects of the surfactant when adsorbed on minerals and when partitioned into SOM. Copyright 2000 Academic Press.

A novel time-domain approach is proposed to synthesize the broadband equivalent model of the differential via based on time-domain reflected (TDR)/transmitted waveforms either measured by TDR or simulated by finite-difference time-domain (FDTD) method. The step responses of the differential via are solved in terms of rational functions by the generalized pencil-of-matrix (GPOM) method. According to the step responses, the broadband macro-/spl pi/ model with each element represented by the optimum pole-residue forms is derived to model the differential via. The equivalent circuits of the macro-/spl pi/ model are synthesized by a systematic lumped-model extraction technique. The accuracy of this approach is demonstrated both in frequencyand time-domain.

A transparent resistive random access memory (T-RRAM) based on ITO/Gd 2 O 3 /ITO capacitor structure is successfully fabricated on Glass substrate by pulse laser deposition (PLD) at room temperature. Under bipolar operation, the ITO/Gd 2 O 3 /ITO device exhibits reliable and stable resistive switching behaviors for more than 200 switching cycles and low operation voltage of −2V/+2V. Furthermore, our device demonstrates nonpolar resistive switching characteristic which exhibits high potential to be applied for the next generation nonvolatile memory.