scholarly journals Optimization Analysis of the Position of Thermometers Buried in Concrete Pouring Block Embedded with Cooling Pipes

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Yaoying Huang ◽  
Tong Xie ◽  
Chunguang Li ◽  
Xiaohui Yin
Keyword(s):  
Temperature Control ◽  
Optimization Algorithm ◽  
Arbitrary Point ◽  
Control Measures ◽  
Temperature History ◽  
Measured Temperature ◽  
Water Pipe ◽  
Average Temperature ◽  
History Of ◽  
Cooling Pipes

The measured temperature of a concrete pouring block depends strongly on the position of the buried thermometer. Only when the temperature measured by the thermometer accurately reflects the actual temperature of the concrete pouring block do reasonable temperature-control measures become possible. However, little research has been done on how to determine the proper position of thermometers buried in a concrete pouring block embedded with cooling pipes. To address this situation, we develop herein a method to determine the position of thermometers buried in a concrete pouring block. First, we assume that the design temperature-control process line characterizes the average-temperature history of the concrete pouring block. Under this assumption, we calculate the average-temperature history of the concrete pouring block by using the water-pipe-cooling FEM, following which the temperature history of an arbitrary point in the concrete pouring block is obtained by interpolating the shape function. Based on the average-temperature history of the concrete pouring block and the temperature history of the arbitrary point, we build a mathematical model to optimize the buried position of the thermometer and use the optimization algorithm to determine this position. By using this method, we establish finite-element models of concrete prisms with four typical water-pipe spacing cases for concrete-dam engineering and obtain the geometric position of the thermometers by using the optimization algorithm. By burying thermometers at these positions, the measured temperature should better characterize the average-temperature history of the concrete pouring block, which can provide useful information for regulating the temperature of concrete pouring blocks.

CFD Simulation of Heating a Cu Pipe with a Safe H2/O2 Flame

2014 ◽  
Vol 611-612 ◽  
pp. 1553-1559
Author(s):  
Lars Kjäldman ◽  
Jouni Syrjänen
Keyword(s):  
Reasonable Agreement ◽  
Cfd Simulation ◽  
Temperature History ◽  
Measured Temperature ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
History Of ◽  
Modeling And Experiments ◽  
Simulation Results ◽  
The Eu

As part of the EU/SME project SafeFlame (www.safeflameproject.eu ) the heating of a Cu pipe by a H2/O2 flame has been modeled and the results are compared to experiments. CFD (Computational Fluid Dynamics) modeling has been utilized to study the flow and combustion in the flame and the heat transfer from the flame to the pipe. The simulation results are compared with the measured temperature history of the pipe at different locations and with the visual flame. The influence of distance between the burner and the pipe and of using two opposite H2/O2 flames on the heating rate of the pipe has been investigated. Reasonable agreement between modeling and experiments has been obtained. The reasons for differences between modeling and experimental results are discussed.

Influence of Water Pipe Cooling on Thermal Stresses in Mass Concrete

2011 ◽  
Vol 137 ◽  
pp. 12-15
Author(s):  
Xin Li Bai ◽  
Ze Yu Wu ◽  
Wen Liang Ma ◽  
Dan Fei Wang
Keyword(s):  
Temperature Control ◽  
Thermal Stresses ◽  
Early Period ◽  
Control Measures ◽  
Mass Concrete ◽  
Late Period ◽  
Water Pipe ◽  
Effective Measure ◽  
Influence Of Water ◽  
Water Pipe Cooling

Temperature field and stress field of a concrete slab in a ship lock chamber are calculated, considering the influence of layered casting. And the influence of water pipe cooling at the early period of constructing, and at the period after constructing, sunshade, pre-cooled concrete etc are taken into account. The expression of finite difference method considering the effect of water pipe cooling is deducted for temperature analysis. Thermal stress calculation results show that the water pipe cooling at the mid-late period is a comparatively effective measure to reduce tensile stress of chamber mass concrete. And an effective temperature control measure is recommended in summer casting, which is that: sunshade + pre-cooled concrete + water pipe cooling (both at early period and at mid-late period). Mid-late period water pipe cooling must last for three months. Combined with other temperature control measures such as summer cover maintenance, winter cover preservation etc, the concrete cracks can be reduced, and the occurrence of large area run through cracks can be avoided.

Anelastic Creep Phenomena in Thin Metal Plated Cantilevers for MEMS

2000 ◽  
Vol 657 ◽  
Author(s):  
Deborah J. Vickers-Kirby ◽  
Randall L. Kubena ◽  
Frederic P. Stratton ◽  
Richard J. Joyce ◽  
David T. Chang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Tunneling Current ◽  
Temperature History ◽  
Measured Temperature ◽  
Control Electrode ◽  
Turn On ◽  
The Past ◽  
History Of ◽  
Displacement Sensitivity ◽  
Vacuum Anneal

ABSTRACTDuring the past several years, we have developed high displacement sensitivity tunneling accelerometers using surface micromachining and metal electroplating techniques. These devices consist of a Au tunneling tip fabricated below a 1-2 μm thick metal cantilever beam of electroplated Ni or Au. A thin film of e-beam evaporated Au on the underside of the cantilever serves as the tunneling counter electrode. In operation, a 100mV bias is applied across the tunneling gap. A larger turn-on voltage is also applied between the cantilever and a control electrode, located on the substrate, to deflect the cantilever and maintain a constant tunneling current of 1 or 10 nA. Typical deflections of the end of 100 μm-long and 250 μm-long cantilevers are 0.5μm during operation. We have observed that the turn-on voltage decreases over time for most devices with a larger drop observed for the Au cantilevers. In all cases, the initial decay of the turn-on voltage was almost completely recoverable after the device was turned off for 24 hrs. This decay was not found to be strongly dependent on the magnitude of the tunneling current, but could be significantly reduced by pre-stressing the cantilever before operation. Finally, a vacuum anneal at 100°C influences the measured temperature dependence of the turn-on voltage. The observed effects appear to be consistent with fatigue and creep phenomena in the cantilevers. These effects are reversible at room temperature and are dependent on the stress and temperature history of the devices. A comparison is made between metal plated and all-Si structures.

scholarly journals Seroprevalence of SARS-CoV-2 Antibodies Among Health Care Personnel at a Health Care System in Pakistan

2021 ◽  
pp. 101053952110110
Author(s):  
Salma Abbas ◽  
Aun Raza ◽  
Ayesha Iftikhar ◽  
Aamir Khan ◽  
Shahzaib Khan ◽  
...  
Keyword(s):  
Health Care ◽  
Control Measures ◽  
Health Care Personnel ◽  
Test Results ◽  
Antibody Testing ◽  
Chain Reaction ◽  
Past Infection ◽  
Infection Control Measures ◽  
History Of ◽  
Polymerase Chain

Health care personnel (HCP) are at high risk for coronavirus disease-2019 acquisition. Serum antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) indicate past infection. Our institution offered SARS-CoV-2 antibody testing to HCP. We surveyed HCP with positive test results to explore past exposure to SARS-CoV-2, details of symptoms during the preceding 6 months, and a history of SARS-CoV-2 polymerase chain reaction testing. A total of 2162 HCP underwent antibody testing. Eight hundred fifty-seven (39.6%) employees tested positive and, of these, 820 (95.7%) participated in the survey. When adjusted for age, males had higher odds of testing positive for SARS-CoV-2 antibodies compared with females (OR = 1.68; 95% CI = 1.37-2.05; P = .00) and clinical staff had higher odds of SARS-CoV-2 seropositivity compared with nonclinical staff (OR = 1.273; 95% CI = 1.06-1.53; P = .01). Implementation of effective infection control measures is essential to protect HCP from coronavirus disease-2019.

scholarly journals Research on concrete temperature control measures in deep hole area of super high arch dam

2021 ◽  
Vol 826 (1) ◽  
pp. 012035
Author(s):  
Yuchen Fu ◽  
Yaosheng Tan ◽  
Chunfeng Liu ◽  
Lei Pei ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Temperature Control ◽  
Arch Dam ◽  
Control Measures ◽  
Deep Hole ◽  
High Arch Dam ◽  
Hole Area ◽  
Concrete Temperature

Hospital Experience with Varicella-Zoster Virus

1986 ◽  
Vol 7 (6) ◽  
pp. 312-316 ◽  
Author(s):  
Keith Krasinski ◽  
Robert S. Holzman ◽  
Rita LaCouture ◽  
Alfred Florman
Keyword(s):  
Infection Control ◽  
Varicella Zoster Virus ◽  
Hospital Staff ◽  
Control Measures ◽  
Varicella Zoster ◽  
Staff Members ◽  
Infection Control Measures ◽  
Serologic Testing ◽  
Care Workers ◽  
History Of

AbstractVaricella-zoster virus (VZV), one of the most common highly communicable agents of disease, stimulates aggressive infection control measures. In a 1-year period, at one hospital, at least 93 inpatients (82 adult patients, 11 pediatric patients) and 2 hospital staff with active varicella-zoster infections served as potential sources of nosocomial infection. Six incidents of exposure to the virus that occurred without the protection of standard infection control precautions were investigated by the infection control surveillance team. One hundred fifty-six patients and 353 hospital staff were exposed. Fifty-one patients had no history of varicella-zoster infection, but only five were susceptible by serologic testing. One hundred one staff members had no history of varicella-zoster, but only 11 were susceptible by serologic testing. These exposures resulted in three secondary varicella-zoster infections, six courses of varicella-zoster immune globulin prophylaxis and furlough of 13 staff members. Epidemiologic investigation consumed approximately 356 hours of staff time, and management of exposed persons cost approximately $41,500. Prospective knowledge of the immune status of health care workers would vastly decrease the time and effort required to control hospital VZV exposures.

Temperature Control and Anti-Cracking Measures for a High-Performance Concrete Aqueduct

2013 ◽  
Vol 405-408 ◽  
pp. 2739-2742 ◽  
Author(s):  
Zhen Hong Wang ◽  
Shu Ping Yu ◽  
Yi Liu
Keyword(s):  
Temperature Control ◽  
Temperature Difference ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Apparent Temperature ◽  
Mass Concrete ◽  
Water Pipe ◽  
Thin Walled ◽  
Water Pipe Cooling

To solve the problem of cracks developing on thin-walled concrete structures during construction, the authors expound on the causes of cracks and the crack mechanism. The difference between external and internal temperatures, basic temperature difference and constraints are the main reasons of crack development on thin-walled concrete structures. Measures such as optimizing concrete mixing ratio, improving construction technology, and reducing temperature difference can prevent thin-walled concrete structures from cracking. Moreover, water-pipe cooling technology commonly used in mass concrete can be applied to thin-walled concrete structures to reduce temperature difference. This method is undoubtedly a breakthrough in anti-cracking technology for thin-walled concrete structures, particularly for thin-walled high-performance concrete structures. In addition, a three-dimensional finite element method is adopted to simulate the calculation of temperature control and anti-cracking effects f. Results show the apparent temperature controlling effect of water-pipe cooling for thin-walled concrete structures.

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