3,317 research outputs found
Digital Detection of Oxide Breakdown and Life-Time Extension in Submicron CMOS Technology
An approach is introduced to extend the lifetime of high-voltage analog circuits in CMOS technologies based on redundancy, like that known for DRAMS. A large power transistor is segmented into N smaller ones in parallel. If a sub-transistor is broken, it is removed automatically from the compound transistor. The principleis demonstrated in an RF CMOS Power Amplifier (PA) in standard 1.2V 90nm CMOS
Scalable Tensor Factorizations for Incomplete Data
The problem of incomplete data - i.e., data with missing or unknown values -
in multi-way arrays is ubiquitous in biomedical signal processing, network
traffic analysis, bibliometrics, social network analysis, chemometrics,
computer vision, communication networks, etc. We consider the problem of how to
factorize data sets with missing values with the goal of capturing the
underlying latent structure of the data and possibly reconstructing missing
values (i.e., tensor completion). We focus on one of the most well-known tensor
factorizations that captures multi-linear structure, CANDECOMP/PARAFAC (CP). In
the presence of missing data, CP can be formulated as a weighted least squares
problem that models only the known entries. We develop an algorithm called
CP-WOPT (CP Weighted OPTimization) that uses a first-order optimization
approach to solve the weighted least squares problem. Based on extensive
numerical experiments, our algorithm is shown to successfully factorize tensors
with noise and up to 99% missing data. A unique aspect of our approach is that
it scales to sparse large-scale data, e.g., 1000 x 1000 x 1000 with five
million known entries (0.5% dense). We further demonstrate the usefulness of
CP-WOPT on two real-world applications: a novel EEG (electroencephalogram)
application where missing data is frequently encountered due to disconnections
of electrodes and the problem of modeling computer network traffic where data
may be absent due to the expense of the data collection process
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Effect of prior cold work on the mechanical properties of weldments
Heat exchanger units used in steam raising power plant are often manufactured using many metres of austenitic stainless steel tubes that have been plastically formed (bent and swaged) and welded into complex shapes. The amount of plastic deformation (pre-straining) before welding varies greatly. This has a significant effect on the mechanical properties of the welded tubes and on the final residual stress state after welding. The aim of the present work was to measure and understand the combined effects of pre-straining and welding on the properties and residual stress levels in stainless steel tubing weldments. Effects of plastic deformation were simulated by plastically straining three identical stainless steel tubes to different strain levels (0%, 10% and 20%). Then each tube was cut into two halves and welding back together. The variation in mechanical properties across weldments was measured using digital image correlation (DIC) and a series of strain gauges (SG). Residual stresses were measured on the 0% (undeformed) and 20% prestrained and welded tubes by neutron diffraction. It was found that the welding process had a marked effect on the tensile properties of parent material within 25mm of the weld centre-line. Evidence of cyclic strain hardening was observed in the tube that had not been pre-strained, and evidence of softening seen in the 10% and 20% pre-strained tubes. Macroscopic residual stresses were measured to be near zero at distances greater than 25 mm from the weld centre-line, but measurements in the 20% pre-strained tube revealed the presence of micro residual stresses having a magnitude of up to 50 MPa
The effect of including a fetus in the uterus model on the risk of fetus mortality through drop test and frontal crash simulations
© 2016 Informa UK Limited, trading as Taylor & Francis Group Computational modelling is an effective way of estimating the risk of injuries and fatalities in road traffic accidents. Computational pregnant occupant modelling has an additional important role in the investigation of the risk of fetus mortality in crash test simulations. In this paper, the effect of including the fetus in the uterus of the pregnant occupant model is investigated. First, isolated drop test simulations with the uterus of the computational pregnant occupant model, âExpectingâ, with and without a fetus are used to show the effect of the presence of fetus in the uterus model. Then âExpectingâ with and without the fetus is used with varying levels of restraint system use, such as fully restrained, âseatbelt onlyâ, âairbag onlyâ and âno restraintâ, in frontal crash simulations, representing five levels of impacts. Maximum strains developed in the uteroplacental interface with and without a fetus are compared in every case. Both simulations predict higher risks of placental abruption when the fetus is included in the model. Simulations with and without a fetus model show that inclusion of a 38-week fetus model causes higher strains in the placental region of uterus
Volumetric evaluation of fat in the renal sinus in normal subjects using stereological method on computed tomography images and its relationship with body composition
Background: The aim of the study was: to describe a simple, accurate and practical technique for estimating the volume of adipose tissue within the renal sinus (RS) using stereological method on computed tomography (CT) images; to establish a population database for volume of fat within the RS from 21 to 80 years of age; to investigate the effect of age, gender, body mass index (BMI) and abdominal diameters on RS fat volume in normal subjects.Materials and methods: We retrospectively reviewed abdominal CT examinations of 240 patients without renal pathology between the ages of 21 and 80 years. There were 6 groups of patients, with 40 patients for each decade.Results: RS fat volumes in the left and right kidney were 5.70 ± 2.87 cm3 and 4.15 ± 2.39 cm3, respectively, in males and 3.51 ± 2.67 cm3 and 2.49 ± 2.16 cm3, respectively, in females. RS fat volume and age were positively correlated for both kidneys (left: r = 0.46; right: r = 0.44; p < 0.001, both), though it appeared to decline after age 70.Conclusions: Quantitative data may allow clinicians to better estimate the age-related RS fat volume changes and help them in decision making
The effect of placenta location on the safety of pregnant driver and her fetus
Placental abruption accounts for more than half of fetal mortality in automobile collisions. In most of the pregnancies, placenta is located at the fundus position of the uterus. However, in real life, placenta can also be found at different locations in the uterus.
The goal of this study is to investigate whether the location of the placenta in the uterus of pregnant driver has a role on the risk of placental abruption in motor vehicle accidents. In addition to the most common fundus position, four other placental locations, namely anterior, posterior, lateral left and lateral right, are considered within the computational pregnant driver model âExpectingâ, and used in collision simulations with impact severities from 15 to 30 kph with 5-kph increments. Scenarios also include four cases where the pregnant driver is fully restrained with three-point seatbelt and airbag, three-point seatbelt only, airbag only and no restraint at all. The maximum strains developed in the utero-placental interface of the model in this set of 64 simulations together with the fundus-location simulations are determined and compared in order to investigate the effect of placental location on the placental abruption prediction.
Placenta located at anterior position is found to be at higher risk than other placental positions considered in this investigation. The results demonstrate that being fully restrained is the safest option and the three-point seatbelt is the most effective restraint system whilst the airbag makes a small contribution to the protection of pregnant driver and her fetus
Dimethyl (1-hydrÂoxy-1,2-diphenylÂethyl)phosphoÂnate
In the molÂecule of the title compound, C16H19O4P, the coordination around the P atom is distorted tetraÂhedral. The aromatic rings are oriented at a dihedral angle of 72.28â
(11)°. IntraÂmolecular CâHâŻO hydrogen bonding result in the formation of five- and six-membered rings. In the crystal structure, interÂmolecular CâHâŻO hydrogen bonds link the molÂecules. There is also a weak CâHâŻÏ interÂaction
New realization of Chua's circuit and verification of chaos by harmonic balance analysis
Chua's circuit, which consists of two capacitors, one inductor, two resistors, one linear voltage-controlled voltage source (VCVS) and voltage-controlled current source (VCCS) type non-linear element has been realized by operational amplifiers. Various dynamical phenomena such as periodic orbit with periods T, 2T, and 4T, single scroll and double scroll similar to the Lorenz attractor have been observed experimentally by changing only the resistance value of the linear resistor R6. The experimental observations have been confirmed by computer simulations and also using harmonic balance analysis
An investigation of artificial pasture establishment under dryland conditions
This study was conducted to determine the suitable mixtures of perennial forage species for the stablishment of artificial pasture under dry conditions in Karapinar-Konya between 2004 and 2006. In this study, complex mixtures of crested wheatgrass (Agropyron cristatum (L.) Gaertner), tall wheatgrass (Agropyron elongatum (Host) Beauv.), intermediate wheatgrass (Agropyron intermedium (Host) Beauv.), smooth brome (Bromus inermis Layss), sheep fescue (Festuca ovina L.), tall oatgrass (Arrhenatherum elatius (L.) Presl.), alfalfa (Medicago sativa L.), sainfoin (Onobrychis sativa Lam.) and garden burnet (Poterium sanguisorba L.) were used. The experiment design was conducted in a randomized block design with three replications. The highest fresh forage yields were obtained from crested wheatgrass, garden burnet and alfalfa mixtures in 2005 and 2006 (1708.1 and 1763.6 kg ha-1, respectively) and the highest dry matter yield was obtained in 2006 (933.9 kg ha-1). The results showedthat mixtures of crested wheatgrass, garden burnet and alfalfa may be used to establish artificial pasture under dryland conditions in similar ecology of KarapĂœnar-Konya.Key words: Artificial pasture, dryland conditions, crested wheatgrass, garden burnet, alfalfa
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Implementation of a simplified method for actuation of ferrofluids
This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Magnetic actuation of ferrofluids is an emergent field that will open up new possibilities in various fields of engineering. The quality and topology of the magnetic field that is being utilized in such systems is determinant in terms of flow properties, flow rates and overall efficiency. Determining the optimal magnetic
field topology to achieve the desired results, and determining the methods by which these magnetic fields are to be generated are central problems of obtaining the desired flow. A healthy comparison of various magnetic field topologies requires a varied set of examples from the most simplified to most sophisticated. Such comparisons are necessary to have a well grounded starting point. This study focuses on a particular pump design that employs a simplified magnetic field topology to obtain ferrofluid flow. The results of this paper such as flow and pressure difference are intended to form a baseline for future reference.Sabancı University Internal Research Grant, no: IACF09-0064
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