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In most concrete-related computer tomography (CT) experiments, detailed information on the damage and fracture process is obtained using nonreal-time approaches, with the CT method constantly regarded as a qualitative method. This study develops a quasi real-time method with the use of experimental instruments. The average CT number is used to analyse the damage and fracture process in concrete specimens and the theory that underlies concrete damage and fracture is improved. Various characteristics of the fracture form in different loading cases are investigated at the macro and micro levels. This study provides a convenient and fast method for qualitatively and quantitatively analysing concrete. First published online: 01 Jun 2015

The calibration detector of a gamma ray monitor (GRM) is designed to detect alpha particles from Am-241 and to send out the coincidence signal to the GRM X-ray detector. The silicon photomultiplier (SiPM), as a novel photon device, is a good candidate to convert alpha-exciting fluorescent photons into electric signals. Three types of SiPMs from SSPM and MPPC, each having an active area of 3 mm x 3 mm, were compared in the matter of the spectra from low-intensity light, dark count, crosstalk probability and I-V curve. The temperature coefficient of SSPM-0710G9MM was also characterized. The application of a SiPM on the GRM has been proved to be feasible.

A thermal control system (TCS) based on the resistance heating method is designed for the High Energy Detector (HED) on the Hard X-ray Modulation Telescope (HXMT). The ground-based experiments of the active thermal control for the HED with the TCS are performed in the ambient temperature range from −15 to 20°C by utilizing the pulse width to monitor the interior temperature of a NaI(Tl) crystal. Experimental results show that the NaI(Tl) crystal's interior temperature is from 17.4 to 21.7°C when the temperature of the PMT shell is controlled within (20±3)°C with the TCS in the interesting temperature range, and the energy resolution of the HED is maintained at 16.2% @122 keV, only a little worse than that of 16.0% obtained at 20°C. The average power consumption of the TCS for the HED with a low-emissivity shell is about 4.3 W, which is consistent with the simulation.

In most concrete CT experiment, the detail information of damage and fracture process is achieved by non-real-time approach, and CT method is always regarded as a qualitative method. In our study, a quasi-real-time method is invented using our experiment instruments. Based on the experiment result, the average CT number is used to analyze the damage and fracture process of concrete specimen, and the theory of damage and fracture process is improved. The different characteristic of fracture form of different loading state is investigated both on the macro and micro aspect. This study provides a convenient and fast method to analysis the concrete qualitatively and quantitatively in the engineering practice.

In numerical simulations, concrete is usually considered as a three-phase material consisting of an aggregate, a cement matrix, and an interfacial transition zone (ITZ). Three-dimensional modeling of concrete usually requires extremely large computational requirements. In this study, an improved random aggregate model for numerical simulations of concrete is developed, which can minimize the number of elements, optimize the ITZ thickness, and create internal cracks and holes. Numerical investigations on the cracks form as well as deflection and tensile strength are also conducted based on three-point bending tests. The simulation results agree well with the experimental results.

An all-fiber optical coherence domain polarimetry (OCDP) is presented, which can increase the detection sensitivity and dynamic range simultaneously. The noise generation mechanism of OCDP and its impact have been studied, and the suppression method of interference beat noise transferred from light source intensity noise is presented. Using polarization beam splitter (PBS) instead of polarization-maintaining coupler, this method completely separated transmission and polarization coupling light in white light interference by optimizing the structure of the optical path. Thus, we can not only increase the signal amplitude of polarization crosstalk, and decrease the system noise. An all-fiber OCDP system has been built, and the detecting sensitivity of polarization crosstalk can reach -98dB, meanwhile, the dynamic range can keep in 98dB. This method realizes the highest performance of the date OCDP technology, and provides an effective measurement and evaluation tools for high performance fiber optic devices and sensor system. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Objective:To evaluate the capacity of a new thoracic electric bioimpedance system to estimate cardiac output compared with the conventional thermodilution method.Design:Prospective, multicenter study.Setting:A university-run county hospital, a university-run U.S. Veterans Affairs hospital, and a uni

To describe the temporal patterns of hemodynamics and oxygen transport in survivors and nonsurvivors of severe trauma in relation to time delays, mortality, and morbidity.Prospective, empiric analysis.University-run, inner city county hospital with a Level I trauma center.A series of 90 consecutively monitored, severely ill trauma patients.We followed 90 patients from admission through their hospital course, and divided the study group into patients with estimated blood loss ofor = 3000 mL and those patients with an estimated blood loss of3000 mL. For each patient, vital signs were recorded in the Emergency Department, operating room, recovery room, and surgical ICU. Hemodynamic and oxygen transport variables were measured at least every 12 hrs for 96 hrs postadmission. Final outcome and complications were recorded.In the first 24 hrs, the values of 60 survivors were significantly higher than the values of 30 nonsurvivors for mean cardiac index (4.52 +/- 1.45 vs. 3.80 +/- 1.20 L/min/m2; p.05), oxygen delivery (670 +/- 230 vs. 540 +/- 200 mL/min/m2; p.01), and oxygen consumption (166 +/- 48 vs. 134 +/- 47 mL/min/m2; p.01). Thirteen (50%) of 26 patients who never attained mean survivors' values (defined as the mean survivors' values listed above) died. Also, 12 (57%) of 21 patients who took24 hrs to attain these values died. In contrast, only five (12%) of 43 patients who reached mean survivors' values inor = 24 hrs died. Thirty-five of 90 patients lost3000 mL of blood; 17 of these 35 patients failed to reach survivors' values within 24 hrs, and 12 (71%) patients died. However, of 18 patients with an estimated blood loss of3000 mL, who reached survivors' values inor = 24 hrs, only two (12%) died. The patients reaching survivors' values inor = 24 hrs,24 hrs, or not at all had similar Injury Severity Scores (28 +/- 13, 26 +/- 13, and 26 +/- 12, respectively) and Trauma Scores (12 +/- 3, 13 +/- 3, and 12 +/- 3, respectively). Only six (12%) of 43 patients reaching survivors' values inor = 24 hrs developed adult respiratory distress syndrome (ARDS), while 27 (57%) of 47 patients showed these values in24 hrs or never developed ARDS.Reaching supranormal circulatory values, especially within 24 hrs of injury, may improve survival and reduce the frequency of shock-related organ failure in severely traumatized patients.

The objective was to test prospectively supranormal values of cardiac index (CI), oxygen delivery index (DO2I), and oxygen consumption index (VO2I) as resuscitation goals to improve outcome in severely traumatized patients. We included patients > or = 16 years of age who had either (1) an estimated blood loss > or = 2000 mL or (2) a pelvic fracture and/or two or more major long bone fractures with > or = four units of packed red cells given within six hours of admission. The protocol resuscitation goals were CI > or = 4.5 L/min/m2, DO2I > or = 670 mL/min/m2, and VO2I > or = 166 mL/min/m2 within 24 hours of admission. The control resuscitation goals were normal vital signs, urine output, and central venous pressure. The 50 protocol patients had a significantly lower mortality (9 of 50, 18% vs. 24 of 65, 37%) and fewer organ failures per patient (0.74 +/- 0.28 vs. 1.62 +/- 0.45) than did the 75 control patients. We conclude that increased CI, DO2I, and VO2I seen in survivors of severe trauma are primary compensations that have survival value; augmentation of these compensations compared to conventional therapy decreases mortality.

We prospectively tested the effect of the early postinjury attainment of supranormal values of cardiac index (or = 4.52 L/min per square meter), oxygen delivery (or = 670 mL/min per square meter), and oxygen consumption (or = 166 mL/min per square meter) on outcome in traumatized patients with an estimated blood loss of 2000 mL or more. The goals in control patients were to attain normal values for all hemodynamic measurements. During the 6-month period, 33 protocol patients and 34 control patients with similar vital signs, estimated blood losses, and severity of injuries were enrolled in the study. Eight (24%) protocol patients died, while 15 (44%) control patients died. The protocol patients had fewer mean (+/- SEM) organ failures per patient (0.76 +/- 1.21 vs 1.59 +/- 1.60), shorter stays in the intensive care unit (5 +/- 3 vs 12 +/- 12), and fewer mean days requiring ventilation (4 +/- 3 vs 11 +/- 10) than did the control patients (P.05 for each). We conclude that attaining supranormal circulatory values improves survival and decreases morbidity in the severely traumatized patient.