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A custom readout electronics for the BESIII CGEM detector
No full textFor the upgrade of the inner tracker of the BESIII spectrometer, planned for 2018, a lightweight tracker based on an innovative Cylindrical Gas Electron Multiplier (CGEM) detector is now under development. The analogue readout of the CGEM enables the use of a charge centroid algorithm to improve the spatial resolution to better than 130 um while loosening the pitch strip to 650 um, which allows to reduce the total number of channels to about 10 000. The channels are readout by 160 dedicated integrated 64-channel front-end ASICs, providing a time and charge measurement and featuring a fully-digital output. The energy measurement is extracted either from the time-over-threshold (ToT) or the 10-bit digitisation of the peak amplitude of the signal. The time of the event is generated by quad-buffered low-power TDCs, allowing for rates in excess of 60 kHz per channel. The TDCs are based on analogue interpolation techniques and produce a time stamp (or two, if working in ToT mode) of the event with a time resolution better than 50 ps. The front-end noise, based on a CSA and CR-RC2 shapers, dominate the channel intrinsic time jitter, which is less than 5 ns r.m.s.. The time information of the hit can be used to reconstruct the track path, operating the detector as a small TPC and hence improving the position resolution when the distribution of the cloud, due to large incident angle or magnetic field, is very broad. Event data is collected by an off-detector motherboard, where each GEM-ROC readout card handles 4 ASIC carrier PCBs (512 channels). Configuration upload and data readout between the off-detector electronics and the VME-based data collector cards are managed by bi-directional fibre optical links
Computational Thermal Fluid Dynamic Analysis of Cooling Systems for Fusion Reactor Components
No full textIn a fusion reactor during plasma operation, the heat loads on plasma facing components can be as high as 5 MW/m2 [1], which should be removed by a proper mechanism to prevent the damage of reactor components. In order to handle such high heat fluxes a suitable heat sink with proper thermal hydraulics is required. In the recent past several heat sinks have been proposed; among which the Hypervapotron heat sink, operating in the highly subcooled boiling regime, is considered as one of the potential candidates. In order to accurately predict the performance of the system, a thermal hydraulic analysis is required. This thesis employs a Computational Fluid Dynamic (CFD) approach to do the thermal hydraulic analysis of the subcooled flow boiling inside the Hypervapotron channel. For this purpose four boiling models are tested using two commercial CFD codes. The four boiling models tested are Rensselaer Polytechnic Institute (RPI) boiling model [2] available in ANSYS-FLUENT 13, Bergles-Rohsenow (BR) model [3] implemented as an external User Defined Function (UDF) in the FLUENT code, the Rohsenow boiling model [4] extended with the capability of transition to film boiling for high heat fluxes available in STAR-CCM+ 7.02, and finally Transition boiling model [4] available in STAR-CCM+ 7.02. These models are used to test the thermal performance of Hypervapotron using the experimental data (showing the variation of temperature with heat flux) obtained from the experiments conducted at Efremov Institute Russia and Joint European Torus United Kingdom. Simulations were conducted using the above mentioned boiling models, the obtained results were compared against the experimental data and also different boiling models are compared with each other whenever possible to test their applicability. From the simulations conducted on the Hypervapotron geometries it is found that the Transition boiling model can capture the thermal performance (in terms of tracing the experimental data) better than any other model both quantitatively and qualitatively, covering the different boiling regimes shown by the experiments ( that is no boiling, nucleate boiling and hard boiling regimes), than the other model
Bloch surface wave label-free and fluorescence platform for the detection of VEGF biomarker in biological matrices
No full textWe report on the detection of an angiogenic molecule Vascular Endothelial Growth Factor (VEGF) in different biological matrices by means of a new integrated biosensing platform exploiting the properties of Bloch surface waves. The new platform takes advantage of a tandem configuration, in which both label-free and enhanced fluorescence detection are implemented. Specifically designed one dimensional photonic crystals were deposited directly on disposable and low cost plastic biochips. A direct sandwich immunoassay was used to detect VEGF in buffer, cell culture supernatant and human plasma at low concentration (ng/mL). The platform enabled the detection of VEGF in all three matrices with high resolution, fast turnaround time (30 min) and in close agreement with the results of enzyme linked immunosorbent assays
High-density surface EMG to investigate muscle activity during standing: implications for the training of postural control with EMG biofeedback in the elderly
No full textBy recording surface EMG using standard bipolar EMG, previous studies have demonstrated that elderlies tend to activate their postural muscles during standing with a higher degree of activity and for a prolonged duration compared with young adults. The EMG biofeedback technique has been widely used to reduce the excessive level of muscle activity in different fields, e.g. the prevention and reduction of low back pain. In this view, EMG biofeedback could be a potential tool to assist aged subjects in reducing the excessive muscle activity during standing balance. However, whether the greater, prolonged activation observed locally in the muscles of aged subjects reflects the activation of the entire muscle is still an open question. It is possible that differences in the activation of postural muscles with aging are more or less expressive than previously appreciated. This thesis aimed at obtaining new insights into the rationale and the effects of the use of EMG biofeedback for the improvement of muscle efficiency during standing in the elderly. It was evaluated whether muscle activation during standing differ between young and aged subjects through a sophisticated detection system for the acquisition of surface EMGs from multiple regions of a single muscle (i.e., high-density surface EMG). Before to test this hypothesis, a methodological issue was addressed to verify whether high-density surface EMG is selective enough to detect during standing: (a) different activation between ankle muscles, as observed with other techniques (intramuscular electromyography); (b) variations in the activity within ankle muscles (i.e., soleus muscles). The results of this methodological study revealed that the medial portion of soleus muscle was activated continuously compared to the lateral portion of soleus and medial gastrocnemius, which were activated intermittently. These results suggest high-density surface EMGs can be used to discriminate the activity between ankle muscles (i.e., medial gastrocnemius and soleus) and muscle activity sampled from different regions of a single muscle (i.e., soleus) can provide estimates more representative of muscle activity during standing. High-density surface EMG was therefore used to assess muscle activity between young and aged subjects during standing. Key results indicate that during standing: (a) tibialis anterior and medial gastrocnemius muscles were active for a longer duration in aged than young subjects; (b) a greater proportion of medial gastrocnemius volume was active in aged individuals. Collectively, these results corroborate previous evidence that elderlies tend to stand with a greater muscle effort than young subjects. Thus, the well-documented attenuation effect of EMG biofeedback on muscle activity may extend to the control of human standing posture with aging. This thesis addressed additional issues which could be relevant to provide more representative EMGs of muscle activity to the subject through EMG biofeedback and to prove the attenuation effect of EMG biofeedback on the activity of lower limb muscles during standing. The following two questions were addressed: i) should EMGs be sampled from both lower limbs to provide more representative information about calf muscles activity? It was observed differences in muscle activity between left and right ankle muscle while young subjects stood at ease. These results indicate muscle activity should be sampled from the ankle muscles of both legs to avoid a biased recording and feedback of muscle activity during standing. ii) Is the attenuation effect of EMG biofeedback on the ankle muscles activity generalized to - or compensated by - other muscles during standing? These findings revealed the attenuation effect of EMG-audio feedback on ankle muscles is not compensated by other lower limbs muscles not included for the feedback. Therefore, the EMG biofeedback may be a promising technique to assist individuals in more efficiently controlling lower limbs muscles during standing. If the short-term, attenuation, effect of EMG-audio feedback on ankle muscles' activity in young individuals observed here is generalized to other populations (e.g., the elderly) and retained after training, then, improvement in postural muscle efficiency may contribute significantly to an ability to maintain standing balance, to respond to unexpected perturbation, standing on narrow stances and walking; with potential implication for the prevention of falls
Service gap deployment: a framework to link quality gaps to service activities
No full textThis paper presents the service gap deployment (SGD), a new method to prioritise crucial to quality activities of a service that does not completely satisfy customer expectations. In the SGD, service activities (SAs) are related to gaps between customer expectations and perceptions so as to identify SAs that may need a redesign or improvement in order to satisfy customer needs. The method, which expands the gaps model of service quality by Parasuraman et al. (1985), supports the design of evolutionary and sustaining improvements of the service parts that generate customer dissatisfaction. Specifically, the SGD introduces three major contributions: 1) it creates a map relating service dimensions to SAs; 2) it highlights crucial to quality activities; 3) it allows a focused improvement of the analysed service. The description is supported by an excerpt from a real application example, concerning the prioritisation of crucial to quality SAs of an airport luggage delivery service
Micromechanical Progressive Failure Analysis of Fiber-Reinforced Composite Using Refined Beam Models
No full textAn efficient and novel micromechanical computational platform for progressive failure analysis of fiber-reinforced composites is presented. The numerical framework is based on a recently developed micromechanical platform built using a class of refined beam models called Carrera unified formulation (CUF), a generalized hierarchical formulation which yields a refined structural theory via variable kinematic description. The crack band theory is implemented in the framework to capture the damage propagation within the constituents of composite materials. The initiation and orientation of the crack band in the matrix are determined using the maximum principal stress state and the traction-separation law governing the crack band growth is related to the fracture toughness of the matrix. A representative volume element (RVE) containing randomly distributed fibers is modeled using the component-wise (CW) approach, an extension of CUF beam model based on Lagrange type polynomials. The efficiency of the proposed numerical framework is achieved through the ability of the CUF models to provide accurate three-dimensional (3D) displacement and stress fields at a reduced computational cost. The numerical results are compared against experimental data available in the literature and an analogous 3D finite element model with the same constitutive crack band model. The applicability of CUF beam models as a novel micromechanical platform for progressive failure analysis as well as the multifold efficiency of CUF models in terms of CPU time are highlighted
State of the Journal
No full textThis is the beginning of the year EiC update on the IEEE Transactions on Computer
An Introduction to Financial Markets: A Quantitative Approach
No full textThe book is organized into five parts. Part One, Overview, consists of two chapters in which we introduce market structures and the basic quantitative problems in finance (portfolio optimization, risk management, asset pricing by no arbitrage). Part Two, Fixed-income assets, consists of four chapters dealing with interest rates, bond pricing, fixed-income markets (including basic derivatives), and interest rate risk management. Part Three, Equity portfolios, consists of four chapters covering decision making under uncertainty and risk measures, mean-variance optimization, factor models, and equilibrium models (CAPM and APT). In the four chapters of Part Four, Derivatives, we deal with dynamic stochastic models (including stochastic calculus), futures and forward contracts, and option pricing in complete and incomplete markets, including model calibration issues. Finally, Part Five, Advanced optimization models, illustrates the role of advanced optimization models, in terms of both building and solving, including stochastic and robust optimization, dynamic programming, decision rules, and conic optimization
