Warpage issues in large area mould embedding technologies

The need for higher communications speed, heterogeneous integration and further miniaturisation have increased demand in developing new 3D integrated packaging technologies which include wafer-level moulding and chip-to-wafer interconnections . Wafer-level moulding refers to the embedding of multiple chips or heterogeneous systems on the wafer scale. This can be achieved through a relatively new technology consisting of thermal compression moulding of granular or liquid epoxy moulding compounds. Experimental measurements from compression moulding on 8” blank wafers have shown an unexpected tendency to warp into a cylindrical-shape following cooling from the moulding temperature to room temperature. Wafer warpage occurs primarily as a result of a mismatch between the coefficient of thermal expansion of the resin compound and the Si wafer. This paper will delve into possible causes of such asymmetric warpage related to mould, dimensional and material characteristics using finite element (FE) software (ANSYS Mechanical). The FE model of the resin on wafer deposition will be validated against the measurement results and will be used to deduce appropriate guidelines for low warpage wafer encapsulation.peer-reviewe

Utilisation of microsystems technology in radio frequency and microwave applications

The market trends of the rapidly growing communication systems require new product architectures and services that are only realisable by utilising technologies beyond that of planar integrated circuits. Microsystems technology (MST) is one such technology which can revolutionise radio frequency (RF) and microwave applications. This article discusses the enabling potential of the MST to meet the stringent requirements of modern communication systems. RF MST fabrication technologies and actuation mechanisms empower conventional processes by alleviating the substrate effects on passive devices and provide product designers with high quality versatile microscale components which can facilitate system integration and lead to novel architectures with enhanced robustness and reduced power consumption. An insight on the variety of components that can be fabricated using the MST is given, emphasizing their excellent electrical performance and versatility. Research issues that need to be addressed are also discussed. Finally, this article discusses the main approaches for integrating MST devices in RF and microwave applications together with the difficulties that need to be overcome in order to make such devices readily available for volume-production.peer-reviewe

The application of support vector machine for speech classification

For the classical statistical classification algorithms the probability distribution models are known. However, in many real life applications, such as speech recognition, there is not enough information about the probability distribution function. This is a very common scenario and poses a very serious restriction in classification. Support Vector Machines (SVMs) can help in such situations because they are distribution free algorithms that originated from statistical learning theory and Structural Risk Minimization (SRM). In the most basic approach SVMs use linearly separating Hyperplanes to create classification with maximal margins. However in application, the classification problem requires a constrained nonlinear approach to be taken during the learning stages, and a quadratic problem has to be solved. For the case where the classes cannot be linearly separable due to overlap, the SVM algorithm will transform the original input space into a higher dimensional feature space, where the new features are potentially linearly separable. In this paper we present a study on the performance of these classifiers when applied to speech classification and provide computational results on phonemes from the TIMIT database.peer-reviewe

Mechanism of sternotomy dehiscence

Research funded by the University of Malta.OBJECTIVES Biomechanical modelling of the forces acting on a median sternotomy can explain the mechanism of sternotomy dehiscence, leading to improved closure techniques. METHODS Chest wall forces on 40 kPa coughing were measured using a novel finite element analysis (FEA) ellipsoid chest model, based on average measurements of eight adult male thoracic computerized tomography (CT) scans, with Pearson's correlation coefficient used to assess the anatomical accuracy. Another FEA model was constructed representing the barrel chest of chronic obstructive pulmonary disease (COPD) patients. Six, seven and eight trans-sternal and figure-of-eight closures were tested against both FEA models. RESULTS Comparison between chest wall measurements from CT data and the normal ellipsoid FEA model showed an accurate fit (P < 0.001, correlation coefficients: coronal r = 0.998, sagittal r = 0.991). Coughing caused rotational moments of 92 Nm, pivoting at the suprasternal notch for the normal FEA model, rising to 118 Nm in the COPD model (t-test, P < 0.001). The threshold for dehiscence was 84 Nm with a six-sternal-wire closure, 107 Nm with seven wires, 127 Nm with eight wires and 71 Nm for three figure-of-eights. CONCLUSIONS The normal rib cage closely fits the ellipsoid FEA model. Lateral chest wall forces were significantly higher in the barrel-shaped chest. Rotational moments generated by forces acting on a six-sternal-wire closure at the suprasternal notch were sufficient to cause lateral distraction pivoting at the top of the manubrium. The six-sternal-wire closure may be successfully enhanced by the addition of one or two extra wires at the lower end of the sternotomy, depending on chest wall shape.peer-reviewe

Proposal for a new ALICE CPV-HMPID front-end electronics topology

This paper presents the proposal of a new front-end readout electronics (RO) architecture for the ALICE Charged-particle Veto detector (CPV) located in PHOton Spectrometer (PHOS), and for the High Momentum particle IDentification detector (HMPID). With the upgrades in hardware typology and proposed new readout scheme in FPGA design, the RO system shall achieve at least five times the speed of the present front-end readout electronics. Design choices such as using the ALTERA Cyclone V GX FPGA, the topology for parallel readout of Dilogic cards and an upgrade in FPGA design interfaces will enable the RO electronics to reach an approximate interaction rate of 50 kHz. This paper presents the new system hardware as well as the preliminary prototype measurement results. This paper concludes with recommendations for other future planned updates in hardware schema

Design of a Quasi-Linear Rail-to-Rail Delay Element with an Extended Programmable Range

peer-reviewe

On the Design of a Linear Delay Element for the Triggering Module at CERN LHC

This paper presents an analytical model of a linear delay element circuit to be employed in the triggering module for the High Momentum Particle Identification Detector (HMPID) at the CERN Large Hadron Collider (LHC). The aim of the analytical model is to facilitate the design of the linear delay element circuit, while maximizing its linearity and delay range. The analytical model avoids the need of time consuming parametric sweeps on the aspect ratios of the various transistors of the delay element in order to optimize it. In addition, the analytical model can be used to predict the variation of the delay with the input tuning voltage. The proposed analytical model is verified via the simulation of the delay element circuit using the 0.18 μm X-FAB technology

Particle Swarm Optimization of a Rail-to-Rail Delay Element for Maximum Linearity

This paper illustrates the use of the Particle Swarm Optimization (PSO) algorithm to maximize the linearity of a rail-to-rail delay element. Previous approaches relied on approximating the piecewise time-delay model of the delay element through either the Newton Polynomial or the Lagrange Polynomial methods. While adequate linearity was achieved in both cases, this could be further improved. This work successfully employed the PSO algorithm to improve the linearity by reducing the mean square error such that the delay element exhibits a spurious-free dynamic range of 29.62 dB, with a delay range of 170.4 ns. The results were verified in Cadence using the X-FAB 0.18 μm technology

Thermography as a method of acquiring competences in Physiology. Application case for hand blood flow control

5 p.The present work proposes a methodological structure as part of the learning of the circulatory system. For this, the application of thermal stress is used, by immersing the hands in cold water to visualize the reperfusion of the hands. Learning, based on the visualization and analysis of thermographic images, allows the acquisition of specific competences at the university level. In graduate studies such as physiotherapy and nursing, the use of virtual tools and materials that allow the acquisition of skills and technical knowledge is essential for the job performance of future professionals. The application of this methodology is proposed in practical sessions of subjects in the area of knowledge of Physiology, to demonstrate and facilitate the understanding of the circulatory system. This approach is framed within the discipline of virtual laboratories since the virtual materials generated can be used for the acquisition of skills and practical competencies, as well as for the evaluation of competencies in e-learning courses. In this way, by recording a pedagogical video that shows a short practice, 5 minutes long, it is possible to establish the necessary knowledge bases to expand them later. This material is easily implementable in any learning management system.S

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe