Papers by Keyword: Leakage

Abstract: This study optimizes 28 nm planar MOSFET technology to reduce device leakage current and enhance switching speed. The specific aims are to decrease subthreshold swing (S.S.) and mitigate drain-induced barrier lowering (DIBL) effect. Silvaco TCAD software is used for process (Athena) and device (Atlas) simulations. For the further development of MOSFET technology, we implemented our device (planar 28 nm n-MOSFET) with high-k metal-gate (HK/MG), lightly doped drain (LDD), multi-spacers, and silicide. Simulation validation shows improvements over other 28 nm devices, with lower static power consumption and notable optimizations in both S.S. (69.8 mV/dec) and DIBL effect (30.5 mV/V).

Abstract: Fluoroelastomer (FKM) and perfluoroelastomer (FFKM) O-rings are to be employed for the construction of a gate valve in a solar thermochemical water-splitting reactor for hydrogen production. To assess the O-rings’ sealing performance during the first stage of the gate valve’s closing process, the compressive response of the materials under the applied gate forces is determined. An accelerated ageing program at 200, 225 and 250 °C for FKM and 250, 275 and 300 °C for FFKM is performed on compressed O-rings and non-compressed O-ring segments for up to 14 days. The aged O-rings’ sealing performance at low forces, and hence at low compressive strain, is evaluated by conducting leakage rate tests in vacuum using a newly developed test stand. Experimental results provide for the tested O-rings data of a minimum compression necessary to guarantee efficient sealing at different thermo-oxidative ageing levels. To investigate the materials’ degradation extent, weight loss measurements are performed on the exposed O-ring segments. In all cases, cumulative weight loss increases with longer exposure times and higher temperatures, while the weight loss rate decreases with exposure time.

Abstract: Air preheaters are used in thermal power plants to preheat combustion air before it enters the furnace by recovering and using waste heat from the flue gas that is supposed to be exhausted at the stack to reduce the work needed by the furnace to combust fuel and improve the boiler efficiency. Air preheater leakage is the bypassing of the cooler ambient air into the flue gas side, reducing the temperature needed to heat the heating elements which transfers the heat into the air side. This negatively impacts the heat transfer effectiveness of the air preheater and the overall thermal efficiency of the plant. This paper aims to review the effectiveness of the soft touch seals applied in a Ljungstrom Type Regenerative Air Preheater installed in a 455 MW (net) Coal-Fired Thermal Power Plant situated in Mauban, Quezon Province in the Philippines in reducing the air preheater leakage through calculations and analysis in compliance with the ASME Performance Test Code to ensure accuracy and repeatability.

Abstract: The visual and instrumental research of the technical condition of historical cultural constructions and their stone additions, documentation of their existing damages, as well as complex development and implementation of further collapse preventing measures and construction durability ensuring measures are presented. Application of processed sand-lime complex mortars based on local raw is offered for blockage of composition cracks during the rehabilitation work taking into consideration some averaged indices of Mape Antique I, Italian “Mapey” firm, similar injection mortar orientation basic characteristics (physical and mechanical characteristics, leakage, viability) and complete laboratory detailed examination results of the component mineralogical and physical and mechanical characteristics of the substances originally used in the construction. The data on local based raw processed sand-lime construction complex mortars (blockage mortar, injection mortar) physical and mechanical characteristics, thermographic dilatometric properties dependence on composition and fastening conditions of mortars are presented

Abstract: This paper provides a thorough investigation on the leakage reason of the ERW steel pipeline in an oil field. Through appearance inspection, physicochemical inspection, metallographic inspection and scanning electron microscope (SEM), it was found that the main reason of corrosions was caused by residual liquid at the bottom of the pipeline and O₂ and CO₂ in the air pressure test. The corrosion medium was large volume of O₂ and CO₂ forming continuously saturated corrosive aqueous solution in small volume of residual liquid, and the corrosion type was the under-deposit corrosion. It is recommended to conduct hot air purging on the pipelined before pressure test for building pipelines in the future, and if the pipeline is not put into use in time, it is recommended to use nitrogen to maintain pressure.

Abstract: Bearing cooler coils connector of 175 MW hydropower plant experienced premature leaks after one year operation and caused an unscheduled shutdown. To avoid the same failure in the future, the leaking bearing cooler coils connector was investigated. Nondestructive tests, such as chemical composition analysis, hardness test, metallographic test, characterization of the filler brazing by scanning electron microscopy – energy dispersive X-ray spectroscopy were conducted. The results confirmed that the bearing cooler coils connector consisted of two types of material namely the flange material which was made of stainless steel 304 and the pipe material which was a Cu/Ni 90/10 and were joined together using brazing process. It was a clearly evidence that leaks occurred in the brazing area and the leakage was due to improper brazing process. It was shown by the excessive gap and a lot of porosity.

Abstract: A hydraulic system simulation model was established suitable for space launch tower’s cable pendulum. And the influences between hydraulic system parameters with working performances were analyzed base on the model. The results show that the interactivity of load, internal leakage of cylinder, characteristics of control valve and relief valve have great effects on the system. Single or combined action of several typical factors can cause abnormal motions of the system. According to the pressure, flow, load and velocity of the system or relative signals in the input and output ports of one valve, some existed problems can be identified compared with the theoretic normal value. This work mainly presents a conduct for the characteristic analysis of the hydraulic system. By selecting appropriate parameters, checking the load and the working performances of some key components, it is effective to master the operation condition.

Abstract: According to the characteristics of methanol leakage hazard, a new kind of foam decontamination agent was prepared and tested. Experiments were conducted in a laboratory-scale apparatus, where the effect of composition and amount on the decontamination performance of the foam was studied in detail. Results showed that the decontaminating efficiency of the foam was above 92% with the volume of foam agent sprayed 3 times of the methanol leaked. Moreover, the thick foam layer could stably cover the liquid methanol for a long time, efficiently inhibiting the volatilization of methanol vapor. Such performance of the foam agent was much superior to that of the commonly used water mist and activated carbon powder. The results are expected to provide useful experimental data and theoretical basis for the practical emergence disposal of methanol leakage.

Abstract: Leakage is a persistent problem in buildings and some other structures, such as dam, bridge and water tower. For a long time, kinds of plugging agents have been developed successfully by modifying organic or inorganic materials. In this paper, the definition, classification and mechanism of plugging agent were introduced and explored in detail. Besides, some application principles and noteworthy matters in engineering were analyzed at well. Furthermore, based on the development of the construction industry in China, some viewpoints of the development prospects of plugging agent were proposed at last.

Abstract: Investigating nuclear power plant containments under accidental conditions obviously leads to the question of possible leakage through cracks of the pre-stressed concrete containment. In the last decades a number of civil engineering R&D programs dedicated to theoretical and experimental analyses have been performed. For the PACE-1450 experiment a leakage testing facility for pre-stressed curved specimen has been built in the laboratory of the Materials Testing and Research Institute (MPA Karlsruhe) at the Karlsruhe Institute of Technology (KIT). The test campaign has now been successfully finished with the evaluation of gained results still ongoing. The first half of the campaign was mainly dedicated to the cracking of the realistically reinforced specimen while the second half was focussing on the leakage behaviour of the cracked specimen. In the tests cold air, heated air and air-steam mixtures were used.