1,724,799 research outputs found
Pediatric Firearm Injury: Comparing age-Adjusted Shock Indices for Prediction of Emergency Interventions
No full textOBJECTIVES: To characterize pediatric firearm injury (PFI) and identify predictors of outcomes relevant to emergency care interventions. METHODS: We conducted a retrospective registry review of pediatric patients (below 18 y) presenting to a single level-1 trauma center located in Seattle, Washington, from 2018 through 2023. PFI patients were compared with the otherwise injured patients by anatomic or physiological severity indices, such as injury severity score (ISS) and 3 types of age-adjusted shock index. The shock indices included shock index pediatric age-adjusted, pediatric shock index, and Advanced Trauma Life Support-based shock index (ATLS-SI). Multivariable logistic regression was performed to identify predictors of the need for transfusion or surgical intervention. RESULTS: Of 2610 total trauma patients, 230 (8.8%) were injured by firearms with a median age of 16.0 years (interquartile range: 14.0 to 17.0) and a male proportion of 80.4%. When compared with other injury mechanisms, PFI was associated with more frequent vascular injuries (PFI, 19.1% vs. others, 4.3%), transfusions (31.7% vs. 10.2%), and surgical interventions (23.5% vs. 6.7%). Among the age-adjusted shock indices, an elevated value of ATLS-SI showed the highest specificities for both outcomes [transfusion, 91.7% (95% CI: 86.3-95.5); surgical intervention, 83.5% (77.2-88.7)] and the strongest association with transfusion at an adjusted odds ratio of 4.84 (1.94-12.06). CONCLUSIONS: From this single-center experience, PFI patients are typically male adolescents, more frequently sustain major vascular injuries, and are more likely to require transfusion or surgery. An elevated ATLS-SI at emergency department (ED) arrival is specific for and predictive of the need for emergency care interventions
Al-induced crystallization of an amorphous Si thin film in a polycrystalline Al/native SiO2/amorphous Si structure
No full textAl-induced crystallization of an amorphous Si (a-Si) thin film in a polycrystalline Al/native SiO2/a-Si structure has been investigated on an atomic level using cross-sectional high-resolution transmission electron microscopy. A 7-nm polycrystalline Al layer was thermally deposited onto a 50-nm a-Si thin film, deposited by low-pressure chemical vapor deposition and covered with a 2.2-nm layer of native SiO2. The a-Si thin film in this structure was partially crystallized at 250 degrees C and completely crystallized at 500 degrees C after 30 min. Lattice fringes of Si(111) were observed in the original Al layer and interfacial native SiO2 layer after the annealing process. From the above results, it was concluded that Al-induced crystallization of the a-Si thin film occurred by interdiffusion of Al and Si atoms through the native oxide layer even though the 2.2-nm native SiO2 layer was not removed completely at the Al/a-Si interface. A possible model, that can be used to explain the Al-induced crystallization phenomena by taking into account the changes that take place within or near the native SiO2 layer during the annealing process, was proposed
Low power low phase noise LC quadrature VCO topology
No full textA simple low power low phase noise LC QVCO (Quadrature Voltage Controlled Oscillator) topology is proposed. The topology minimizes phase noise by eliminating the contributions from the tail current source and coupling transistors. With no more than 3.36mW power consumption from a 1.2 V power supply, the VCO achieves -124 dBc/Hz phase noise performance at 1 MHz offset from the 2.85 GHz carrier frequency
Schedulability analysis of time-constrained cluster tools with bounded time variation by an extended Petri net
No full textCluster tools for some wafer fabrication processes such as low-pressure chemical vapor deposition have strict wafer delay constraints. A wafer that completes processing in a processing chamber should leave the chamber within a specified time limit. Otherwise, the wafer suffers from severe quality troubles due to residual gases and heat within the chamber. An important engineering problem is to verify whether for given task times there exists a tool operation schedule that satisfies the wafer delay limit. There have been studies on the problem, which all assume deterministic task times. However, in reality, the task times are subject to random variation. In this paper, we develop a systematic method of determining schedulability of time-constrained decision-free discrete-event systems, where time variation can be confined within finite intervals. To do this, we propose an extended Petri net for modeling such systems. We then develop a necessary and sufficient condition for which there always exists a feasible schedule and one for which there never exists any feasible schedule. We develop a graph-based computational procedure for verifying the schedulability conditions and determining the worst-case task delay. We demonstrate how the procedure can be used for cluster tool engineering to control wafer delays against wafer alignment failures and time variation. Note to Practitioners-Many automated systems such as cluster tools for semiconductor manufacturing repeat predetermined cyclic work cycles. However, they may have strict time window constraints between a pair of events and also their activity times are subject to random variation. However, the random variation can be confined within a finite range with some confidence level. Our proposed method can verify whether such systems can satisfy the time constraints. By using our proposed method, engineers can quickly examine validity of their engineering decisions such as tool configuration and process time choices
Fatigue crack opening stress based on the strip-yield model
No full textThe modified strip-yield model based on the Dugdale model and two-dimensional approximate weight function method were utilized to evaluate the effect of in-plane constraint, transverse stress, on the fatigue crack closure. The plastic zone sizes and the crack opening stresses considering transverse stress were calculated for four specimens: single edge-notched tension (SENT) specimen, single edge-notched bend (SENB) specimen, center-cracked tension (CCT) specimen, double edge-notched tension (DENT) specimen under uniaxial loading. And the crack opening behavior of the center-cracked specimen under biaxial loading was also evaluated. Normalized crack opening stresses sigma(op)/sigma(max) for four specimens were successfully described by the normalized plastic zone parameter Delta omega'(rev)/omega' considering transverse stress, when Delta omega'(rev) and omega' are the size of the reversed plastic zone at the moment of first crack tip closure and the size of the forward plastic zone for maximum stress, respectively. The normalized plastic zone parameter with transverse stress also was satisfactorily correlated with the behavior of crack closure for CCT specimen under biaxial loading. (C) 2000 Elsevier Science Ltd. All rights reserved
Scattering from an annular slot on a radial waveguide
No full textThe boundary-value problem of scattering from an annular slot on a radial waveguide is solved. The scattered fields are expanded in terms of eigenfunctions based on the Fourier series and Hankel tran, form. Boundary conditions are enforced to constitute a set of simultaneous equations. A fast convergent series solution is obtained using residue calculus. Computations are performed to investigate radiation and coupling by an annular slot on a radial waveguide. Favorable agreement is observed between our theory and other existing results. (C) 2005 Wiley Periodicals, Inc
An analysis of upset forging of square blocks considering the three-dimensional bulging of sides
No full textA simple kinematically admissible velocity field for three-dimensional deformation in upset forging of square blocks is proposed which considers not only the sidewise spread but also bulging along thickness. From the derived velocity fields the upper bound load andt he deformed configuration are determined by optimizing some given parameters. Experiments are carried out with annealed AISI 1015 steel billets at room temperature for different thickness and lubrication conditions. The theoretical estimates both in forging load and the deformed configuration are in good agreement with the experimental results. It is shown that the velocity field proposed in this work can be used conveniently for the prediction of forging load and deformation in upset forging of square blocks. © 1985
Realization of dynamic walking for the humanoid robot platform KHR-1
No full textThis paper presents three online controllers for maintaining dynamic stability of a humanoid robot and describes simplified walking patterns for easy tuning in real experiments. The legs of a humanoid robot are relatively long and serially connected with compliant force/torque sensor at the ankle. This architecture has the inherent characteristics of a lightly damped system. Most research on balance control overlook the deterministic vibration caused by structural compliance. In addition, the vibration was not positively considered to improve the characteristics of the system. Therefore, a simple inverted pendulum model with a complaint joint is proposed. The proposed model has an advantage in easy parameter identification by experiment. For this model, the damping controller that increases system damping is proposed as a balance controller. Furthermore, the performance of maintaining balance against external forces is experimentally shown. A landing orientation controller at the ankle joints is presented to manage fast and stable ground contact. A landing position controller is implemented in order to modify the prescribed trajectory of the swing foot and to reduce the landing impact during unexpected landing. The effectiveness of the proposed controllers is confirmed by walking experiments that have been applied on the KAIST humanoid robot platform KHR-1
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