Interfacial Effects During Thermal Cycling of Cu-Filled Through-Silicon Vias (TSV)

Large shear stresses may develop at interfaces between dissimilar materials during thermal excursions when there is a significant difference in their coefficients of thermal expansion. The shear stress may cause interfaces to slide via diffusional process, thereby accommodating the relative dimensional changes between the two materials. This phenomenon presents a significant reliability issue in three-dimensional (3-D) interconnect structures involving through-silicon vias (TSVs), which are subjected not only to continuous thermal cycling but also to large electric current densities during service. This paper reports experimental evidence of interfacial sliding between Cu and Si in Cu-filled TSVs during thermal cycling conditions, and in the presence of electric current. Two different thermal cycling conditions were used: (i) small ΔT thermal cycling (−25°C to 135°C) and (ii) large ΔT thermal cycling (25°C to 425°C). Prior to thermal cycling, a few Cu-filled TSV samples were annealed for 30 min at 425°C. Cu intruded inside Si in nonannealed samples during small ΔT thermal cycling, whereas protrusion of Cu relative to Si occurred during all other thermal excursions. Application of electric current biased the net displacement of the Cu in the direction of electron flow, leading to enhanced protrusion (or intrusion) of Cu relative to the thermal cycling only (i.e., without electric current) condition. A simple one-dimensional analytical model and associated numerical simulations are utilized to rationalize the experimental observations.     

Analyzing the effects of inventory cost setting rules in a disassembly and recovery environment

In this study we consider a disassembly and recovery facility receiving end-of-life products and facing demand for a specific part that is disassembled from the product and then recovered. The disassembly and recovery operations can be either performed before hand, or upon customer arrival. In the latter case, a discount on the selling price is applied to compensate the customer for waiting for the completion of the disassembly and recovery operations. One of the difficulties faced in planning for such a system is the determination of the opportunity cost associated with carrying recovered parts inventory. The difficulty arises in seeking the value added to the part given the costs incurred for maintaining the product return, disassembly and recovery costs and revenue earned from the hulk, that is the remaining product after the disassembly of the part. The main objective of the study is to investigate the effect of different rules to determine this opportunity cost on the performance of the system. Six rules are considered in the study. The performance of the rules is assessed by a computational study under an approximate inventory control policy.     

Detection of sources using bootstrap techniques

Source detection in array processing can be viewed as a test for equality of eigenvalues. Such a test is proposed, based on a multiple test procedure that considers all pairwise comparisons between eigenvalues. Using the bootstrap to estimate the null distributions of the test statistics results in a procedure with minimal assumptions on the nature of the signal. Simulations show that the proposed test is superior to information theoretic criteria such as the MDL, which are based on Gaussian signals and large sample sizes. Performance in most cases exceeds the more powerful sphericity test     

Stabilization of linear systems under nonlinear stable diagonalperturbations

Stability of linear, time-invariant, multi-input multi-output unity-feedback systems is considered under nonlinear, time-varying, stable perturbations. Necessary and sufficient conditions are obtained for stability of the perturbed system and specialized for the case of one arbitrary failure whose location is unknown. Controller design methods are developed ensuring stability under an unknown stable failure of at most one arbitrary sensor or actuator     

Parameterization of decoupling controllers in the unity-feedbacksystem

The problem of decoupling in the linear, time invariant, multiinput-multioutput unity-feedback system is studied. A parameterization of all stabilizing decoupling controllers and all achievable decoupled closed-loop transfer functions is obtained for full-row rank plants which do not have any coinciding poles and zeros in the undesirable region of the complex plane     

PID Stabilization of MIMO Plants

Closed-loop stabilization using proportional-integral-derivative (PID) controllers is investigated for linear multiple-input-multiple-output (MIMO) plants. General necessary conditions for existence of PID-controllers are derived. Several plant classes that admit PID-con- trollers are explicitly described. Plants with only one or two unstable zeros at or "close" to the origin (alternatively, at or close to infinity) as well as plants with only one or two unstable poles which are at or close to origin are among these classes. Systematic PID-controller synthesis procedures are developed for these classes of plants.     

Reinforcement effects of multiwall carbon nanotubes and graphene oxide on PDMS marine coatings

Poly (dimethyl siloxane) (PDMS) is a model silicon elastomer used as marine fouling-release coating, because it meets the fouling-release zone conditions of the Baier curve. However, weak mechanical properties limit its use. In this aspect, incorporation of carbon nanoparticles into PDMS is a common method for improving its mechanical properties. Since effective dispersion of nanofillers into polymer matrices is a challenge, a major aim of this study was to examine the PDMS mechanical reinforcement by developing different dispersing methods of pristine MWCNTs into PDMS matrix. SEM images of nanocomposites prepared using dispersion methods 1 and 2 revealed the formation of aggregates which subsequently affected the overall mechanical performance of the samples. Also, the effect of p-MWCNTs content and nanoparticle type [carboxyl-functionalized-MWCNTs, graphene oxide (GO)] on the mechanical properties of the nanocomposites was evaluated. Incorporation of p-MWCNTs did not alter drastically the critical surface energy value of neat PDMS, which subsequently influenced antifouling and cleaning performance of nanoreinforced coatings. To evaluate antifouling and cleaning performance of the nanocomposite coatings, seawater immersion tests were conducted. In conclusion, MWCNTs and GO increased the mechanical strength of the matrix, whereas they contributed to a small extent to the improvement in antifouling and cleaning performance of the composites.     

Removal of disperse dye from aqueous solution by novel adsorbent prepared from biomass plant material

The adsorption of Disperse Orange 25 (3-[N-ethyl-4-(4-nitrophenylazo) phenylamino] propionitrile) onto activated carbon was investigated in a batch system with respect to contact time, carbon dosage, pH and temperature from aqueous solutions. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The Langmuir isotherm model agrees with the experimental data well. Maximum adsorption capacity (q_max) of Disperse Orange 25 onto adsorbent was 118.93 mg g⁻¹ at 20 °C. The first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated as well. The experimental data fitted very well to pseudo-second-order kinetic model. The results show that activated carbon prepared from Euphorbia rigida by sulfuric acid chemical activation could be employed as low-cost material to compare with commercial activated carbon for the removal of disperse dyes from effluents.