bluuebunny/crossref_metadata_2025 huggingface dataset:
Significant Reduction in OPEX by Improving Efficiency of GC Test Facility
Authors: Al-Shammari B..
Published: October 2017

Kuwait Oil Company is currently producing around 3.2 MMBOPD out of which the major share of 1.7MMBOPD is produced by South East Kuwait asset (SEK). SEK has 14 Gathering centers (GC) with an average of 100 flowing completion per GC. It has always been a challenge to test individual completion to get correct rate and other well test parameters not only to calculate the exact production potential of the GC but also to back allocate the rates to the reserves produced. Since long time the prevailing practice in SEK was to test individual wells in the GC using GC test separator and as well as testing wells by portable test units. The rates obtained from above two methods were used to be compared with the expected calculated rates based on PI calculations and other reservoir properties. The GC test is done by diverting the well manually to GC test separator which does not incur any additional cost to the company compared to portable test which done by service company hired by KOC well surveillance department with associated operational cost.

The need of portable test were justified because the old GC test facilities occasionally were giving inaccurate results and the results were used to be rejected by Field development engineers resulting in a repeat test request of portable test. This was not only taking long time to get the correct data but also add extra operational cost component to the company.

In 2014-15 it was proposed to upgrade the GC well test facilities with state of the art technology. The upgrade was completed in November15 and the GC test facilities became operationally available in Dec 15. In spite of initial difficulties and inaccuracies in the tests results the GC test units were finally accepted in Jan16 to be accurate for all the GC’s after satisfactory comparison between the portable and GC tests results.

There has been a great cost saving by the above in operating expenditure (OPEX) of SEK well surveillance. The number of portable tests has been reduced to 200 from the earlier average number of 1400 plus per year resulting a direct saving of around USD 3.6 million
How Private Cloud Solution Go Beyond the Conventional Infrastructure Solution for Jurassic Kuwait Digital Integrated Field
Authors: Al-Mai N.. , Najem N.. , Al-Shammari R.. , Leeri A.. , Robert H.. , Divakaran D.. , Farid A.. , Johnston B.. , Arzhilovskiy S..
Published: October 2017

Kuwait Digital Integrated Field (KwIDF Jurassic) is a complex field located in the North Kuwait. As with many other Digital oil field projects the IT challenges are numerous. The current infrastructure is based on physical servers and resource handling is challenging. Require integrated infrastructure solution to build new workflow demands and to cater large amounts of real-time data being retrieved wells and facility sources.

Adoption of Cloud computing for oil and gas is increasing over the last few years, this document primarily focus on Private Cloud strategy for KwIDF Jurassic. A comprehensive assessment was done with the KOC IT Stakeholders, during the in assessment phase captured all the challenges and we ensure the Security is prime requirement accessing the KwIDF applications, One of the prominent challenges was to have offered in cloud computing is the centralized data-handling requirements, the solution creates such a change in technological as well as new workflows Validation tests on the KOC recommended hardware was successfully completed. This delivers the learning and experiences for cloud road map and strategy creation for KOC IT,

Based on the validation proof of concept results, the solution private cloud implementation framework was designed primarily on Virtual Desktop Infrastructure (VDI). Includes Kernel-Based Virtual Machine (KVM) virtualization technologies, the VDI Solution will integrate with KOC Application cluster, the VDI Solution provides anytime, anywhere access to KwIDF applications with improved security. The Cloud and Virtualization solution will improve the application delivery system with high performance for the provide solution and enhance operational and business outcomes. Adding private cloud platform can take the project to a new level of business improvement and enhance operational performance.

The potential benefit of implementing secure cloud includes benefits like high-resource utilization and IT resource management for operations team in Datacenter.. Providing high availability and disaster recovery, also allow user self-service provisioning templates with rapid delivery of virtual machines, the whole solution is aligned with KOC CITG business strategy.
Utilizing Entire LWD Dataset from Horizontal Wells in Thin Bed Siltyshale Layers of BGSU to Extract Maximum Value
Authors: Kotecha R. K. , Al-Zaabi R. Z. , Al-Sabea S , Ali F.. , Al-Rabah A. A. , Bu-Qurais A. F , Haryono R.. , Haider E.. , Altemeemi B.. , Alharbi A..
Published: October 2017

Drilling in thin reservoirs is challenging task. But with easy pockets gone the reservoirs left are less than 5 to 10 feet and it becomes difficult to steer well exclusively in the sweet spot or sand in thin payzone. It is this reservoir which offer task to drill horizontal well and produce maximum where otherwise it would be difficult to produce even 200-300bopd from this thin layer of silty shales. Moreover the thin beds are like appearing or vanishing as we drill ahead due to facies change. This needs complete attention till the well reaches Target Depth (TD). Even a small fault of sub-seismic nature of 2 feet throw can offset the well from the sweet zone. But with advanced logging tools used in two wells helps to understand the nature of lithology and its productivity. Best application of this tools are in silty shales in Burgan Sands Upper (BGSU) which generally show high GR and often this leads to misjudgment of well not being in sweet spot.

Logging While Drilling (LWD) logs and inversion was used whether the well is in productive zone or not. The LWD tools now have Azimuthal GR, density and resistivity. This gives a holistic picture of the lithology in the roof side or the bottom side of the lateral section. The wells under discussion were drilled with such advanced version of distance to boundary tool.

After well was steered till TD, the data was processed by Petro-physicist to indicate possible payzone to decide completion. But due to high GR which is often prevalent in Burgan Sand Upper (BGSU) the entire well bore was not getting classified as potential payzone. But after looking the inversion and all LWD data sets it was conveyed that the Inflow Control Device (ICD) can be lowered for entire well bore length. As an outcome advanced ICD was lowered also against high GR zones which otherwise were not getting classified as potential payzone, and well were completed. The well was put on production starting with 1300 BOPD on 32″ choke and still after 18 months continues to produce. PLT results show that the zones indicating high GR and with poor log properties were also contributing oil. The paper discusses these wells and utilization of complete data set acquired at time of drilling and taking completion decision accordingly. The output of data of LWD has been fully utilized to complete the well successfully and given the confidence of doing so in other wells. In fact this experience was used in another similar looking well with unfavorable parameters and successfully completed.
Sour Gas Occurrences in Kuwait and the Mitigation Challenge
Authors: Hofmann A.. , Al-Khamiss A.. , Andriyany R.. , Taqi H.. , Malekzadeh R.. , Strien W. van
Published: October 2017

Numerous oil and gas reservoirs in Kuwait are suffering from H2S contaminations. The H2S concentrations in the affected reservoirs vary significantly from low ppm ranges up to 40%. The H2S concentration levels are related to the generation processes. The high H2S concentrations observed in the Lower Jurassic reservoirs can be related to the TSR process. The dominant H2S generation process in the Upper Jurassic and Lower Cretaceous reservoirs is the thermal cracking of the organic sulphur compounds (OSC) occurring in the Najmah and Sargjelu source rocks. The H2S contaminations observed in the Cretaceous reservoirs show indications of multiple H2S sources. The bulk of the H2S in these reservoirs is generated in situ by the BSR process. In some fields clear indications for H2S migrated from deeper horizons e.g. via faults are observed.

H2S contaminations are also observed at the top site facilities at various stages of the production process. The source for those contaminations is only partly in the subsurface. In several cases a distinct increase of the H2S contaminations of the fluids on its way from the reservoir well to the processesing facilities is observed.

New sampling and analytical technologies tailored to the H2S problematic have been developed, which support the selection of the appropriate mitigation or remediation strategy. The utilization of modern low cost DNA sequencing technologies for the analysis of the bacteria and archea species provide essential information for the design of appropriate chemical cocktails for the mitigation.

Reservoir modeling and forecast technologies have been developed to predict the development of the H2S concentrations in a reservoir. However, for a reliable forecast - irrespective which modeling system or tool is applied - the understanding of the H2S generation process is essential. Furthermore good quality and reliable H2S measurements are mandatory for the history match.

The mitigation and remediation of H2S is a major cost factor in the field development and operations. Field souring i.e. the increase of the H2S concentration during field life is the worst case scenario, which could cause major investments to assure field production. Not only the costs for the H2S treatment materials (e.g. biocides, nitrate) but also the investments in corrosion inhibitors, H2S resistant pipes, valves, filters, and the upgrade of the processing facilities have a large financial impact. Furthermore HSE related measures and required safety and monitoring systems are increasing substantially the operation costs.

In view of KOC's ambitions to increase the oil production by 20% by 2020 and the subsequently expected increase of H2S production, a contry-wide coordination of the treatment concepts for the H2S could improve the efficiency of the mitigation operations and could potentially reduce the investments and operation costs related to the sour gas issue.
Advances in Spacer Technologies for Improved Zonal Isolation Results in Challenging Deep Deviated HPHT Wells Containing Heavy Oil Based Muds
Authors: Brandl Andreas , Doan Angela Anh , Alegria Adriana Estela
Published: October 2017

Insufficient wellbore cleaning prior the cementing job is considered to be the biggest single factor leading to poor zonal isolation results. A mud-spacer-cement program with suitable fluid needs to be carefully engineered for the given wellbore conditions to improve cementing quality. We discuss optimum spacer design features which are critical for the successful cementation of deep deviated HPHT wells containing heavy oil based muds and review a simulated scenario. Advanced lab test methodologies beyond industry standards are utilized to model more accurately the given complex downhole conditions.

A simulated >20,000 ft highly deviated wellbore was characterized by HPHT bottomhole conditions and the rheological performance of the cement spacer was critical to job success. The well needed a stable cement spacer that would not settle-out on the low side of the >14,000 ft horizontal section, which would potentially put the well at risk. The 16.17 ppg mud required an even higher-density spacer system to clean it effectively. But conventional high-density spacer systems only compound the settling challenge and the well's anticipated bottomhole temperature of 350°F was expected to compromise any additives that might stabilize the fluid systems. Therefore a lab study about spacer stability was performed using a HPHT rheometer and the dynamic settling test – an industry standard which was actually established for cement slurries but not for spacer fluids. We found that a conventional spacer failed at 350°F by showing a rapid decline in rheology to almost zero viscosity and severe settling. To overcome the settling issue, provide stability, and maintain a sufficiently high rheology profile at given 350°F, we re-designed the spacer by using a modified biopolymer which shows a delayed hydration and viscosification over time successfully counteracting the destructive thermal effects.

The mud-spacer-cement fluid train was eventually optimized showing good fluid compatibility and maintaining within the narrow, 1.6 ppg margin that separated the pore pressure from the fracture gradient. The cementing job was designed using an advanced fluid displacement software, which predicted high mud removal efficiency under these challenging conditions. In order to enable proper mud displacement, the Friction Hierarchy—a key design factor that is often difficult to achieve under the extreme HPHT well conditions—was achieved with the new spacer concept.
Integrated Planning and Drilling Approach Efficiently Navigates the Uncertainty of a Challenging Horizontal Evaluation Well
Authors: Ghamdi Muataz Al , Yami Fahad Al , Shafy Mohamed El , Beltagy Mohamed El
Published: October 2017

Horizontal, heterogeneous reservoirs of low permeability present various challenges and drilling risks. The likelihood of encountering potential problems can be greatly increased when there is a minimal understanding of geology and pressure regime in the area of interest. A similar case was tackled while drilling an observation well.

The drilling challenges were carefully recognized and highlighted to be properly addressed. Planning and risk mitigation measures included the introduction of a set of drilling and tripping practices to minimize potential risks while drilling the well. Details of the comprehensive evaluation program and logging tools were discussed along with drilling fluid design. In addition, rigorous efforts were exerted on BHA design, drilling dynamic modeling, torque-and-drag simulation, and hydraulic management.

The integrated planning and drilling approach implemented in the subject well has ensured the safety of drilling operations through real-time formation pressure evaluation, which has allowed for quick mud weight control while drilling. In addition, the drilling fluid was pre-treated with sized bridging materials to build an impermeable filter across the anticipated streaks of permeable intervals. Improved drilling and tripping practices have helped in drilling a trouble-free well, where the risk of differential sticking was minimized. An advanced well-engineering software was used to design the rotary steerable system (RSS) and the logging-while-drilling bottomhole assembly to reduce the severity of stick/slip vibration and minimize wellbore contact across the lengthy BHA. This has led to an enhanced and optimized drilling performance, which was complemented by real-time monitoring to allow for on-the-spot decision making. The collected data in the well will help in identifying and modeling reservoir characteristics in terms of porosity, permeability, formation pressure, and fracture identification.

The employed integrated planning and drilling approach has successfully enabled meeting the objective of a challenging well in which a high level of uncertainty was present. The delivery of the well will help in making better reservoir management decisions and increasing the confidence in geological and petrophysical models.
Grain Sorghum Response to Nitrogen Fertilizer following Cover Crops
Authors: Fontes Giovani Preza , Tomlinson Peter J. , Roozeboom Kraig L. , Ruiz Diaz Dorivar A.
Published: October 2017

Grain sorghum growth and development was affected by cover crop and N management.

Sorghum–sudangrass cover crop prior to grain sorghum required N to maintain yield.

Late maturing soybean cover crop increased grain sorghum yield at suboptimal N rates.

Late maturing soybean cover crop, N fertilizer replacement value of 44 kg N ha–1.

Cover crops (CCs) can affect N fertilizer management by influencing nutrient cycling and N fertilizer requirement. Cropping systems with different CCs were established in 2007 to examine the response of sorghum [Sorghum bicolor (L.) Moench]. Four CC treatments {summer legume, late‐maturing soybean [LMS; Glycine max (L.) Merr]; summer non‐legume, sorghum–sudangrass (SS; Sorghum bicolor × Sorghum bicolor var. sudanese); winter legume, crimson clover (CL; Trifolium incarnatum L.), and winter non‐legume, daikon radish (DR; Raphanus sativus L.)} as well as double‐crop soybean (DSB) and chemical‐fallow (CF) treatments were imposed after wheat (Triticum aestivum L.) harvest in a wheat–sorghum–soybean cropping system. Five N rates (0, 45, 90, 135, and 180 kg N ha–1) were applied to sorghum within 2 wk of planting. Aboveground sorghum biomass was collected after physiological maturity to determine total N uptake and grain yield. The cropping system managed with LMS increased grain yield (>9%), compared to other CCs and CF with zero N application. Cropping systems including CL, DR, and DSB had similar effects on grain yield relative to CF when N fertilizer was applied. Increasing N rates significantly increased grain yield and N uptake of grain sorghum following SS, indicating that soil N was limited in this cropping system. The addition of LMS as a summer legume CC has the potential to contribute N and replace CF, thus improving management of N resources.
Land‐Use‐Dependent Change in the Soil Mechanical Strength and Resilience of a Shallow Volcanic Ash Soil in Southern Chile
Authors: Dörner José , Horn Rainer , Dec Dorota , Wendroth Ole , Fleige Heiner , Zúñiga Felipe
Published: October 2017

Core Ideas

Land use change had a great impact on the spatial variability of Aquands' physical properties.

Mechanical strength increased as a consequence of the land use change.

The soil's physical resilience presents spatial variability.

Aquands with a bulk density close to 0.65 g cm–3 can be considered to be compacted.

Aquands are shallow volcanic ash soils, locally called Ñadi, which cover an area of 475,000 ha in Chile and have undergone intensive land use changes from secondary native forest (SNF) to naturalized grasslands (NG). This study analyzed the impact of this land use change in a Ñadi soil on the spatial changes in its mechanical strength and the consequences on pore functions and soil resilience. The change from SNF to NG occurred in 1980 because of a forest fire. We measured the volumetric water content and penetration resistance between 0 and 10 cm depth at 98 grid points across the domain (SNF and NG). Near each grid point, undisturbed soil core samples were collected to measure soil precompression stress (Pc), soil resilience after the application of mechanical stresses and water saturation via capillary rise, and the changes in air permeability (ka). After the application of mechanical stresses (to 400 kPa), the soil presented a land‐use‐dependent soil deformation and a limited, spatially variable soil resilience, which homogenized the ka across the field. Despite a bulk density of 0.65 g cm–3, these soils must be described as highly compacted and defined by high soil mechanical strength (Pc > 60 kPa) with small values of air capacity (<8%) and permeability (<1 log μm2). To design proper schemes for land use planning of these specific soils, further analyses are required, as is a definition of a minimal Ñadi soil depth to support a productive system without detrimental effects on the ecosystem services.
The impact of rotor elastic suspension settings on the acceleration of the automatic balancer compensating mass
Authors: Strautmanis Guntis , Mezitis Mareks , Strautmane Valentina
Published: October 2017

Experimental studies of the vertical rotor with the automatic balancer ball type with a torus-shaped body with a cross section of the round form showed that the compensating masses are not accelerated to its operating speed at the each start of the rotor. The work is devoted to clarify the effect of the stiffness of the rotor elastic suspension on the acceleration process of compensating mass.
Dynamic analysis of localized defects in rolling bearing systems
Authors: Song Mengmeng , Xiao Shungen , Huang Lixia , Li Wanxiang
Published: October 2017

In this paper, the dynamics of rolling bearing with localized defects of the outer ring and rolling element are investigated. In order to study the nonlinear dynamical behaviors of the rolling bearing precisely, a novel dynamic model of the rolling bearing is established based on the Lagrangian approach. By setting 0.2 mm, 0.4 mm and 0.6 mm local defects on the outer ring and rolling element of bearing respectively, the results demonstrate that the amplitude of the rolling bearing is more intense as the local defect size increases, and the acceleration amplitude fluctuation is more significant than the velocity. In addition, in the case of the same defect size, the vibration of the rolling element defect is more intense than the vibration response caused by the outer ring defect.
Maintenance decision-making based on remaining useful life considering economy optimal targets and its application
Authors: Jia Yunxian , Liu Xin , Wang Qiang , Zou Xiao
Published: October 2017

Components in engineering systems are degenerated due to different conditions. In order to avoid serious loss, the components need to be replaced before failure occurs to provide the intended and safe operation of the systems. Therefore, the maintenance decision-making method based on remaining useful life considering different optimal targets was presented in this paper, and the purpose of this method was to find an optimal choice of maintenance actions to be performed on a selected group of machines for engineering systems. Then, the optimal maintenance interval based on the minimum expected cost rule was discussed, and the arithmetic reduction of intensity model was introduced to describe the influence of remaining useful life. Finally, a full life experiment of gearbox was given to demonstrate the preferred decision-making with the influence of the remaining useful life.
Research on effectiveness evaluation method and application of quality management system of manufacturing enterprise based on interval-valued hesitation fuzzy set
Authors: Yao Yu Chen
Published: October 2017

Based on acquaintance of effectiveness of quality management system of manufacturing enterprise, the evaluation index system is structured by confirmation of production conditions and other seven respects which include effectiveness of validation, effectiveness of document management, effectiveness of production management, effectiveness of quality assurance and quality control, effectiveness of commissioned production and inspection, effectiveness of Issue and recall of products and effectiveness of self-checking; the assessment model of effectiveness of quality management system of manufacturing enterprise based on interval-valued hesitation fuzzy set is structured and the feasibility of theoretical research was validated by concrete cases.
Analytical method of designing a comparable milling machine model based on Matlab/Simulink
Authors: Osman Bashir , Zhu Haitao
Published: October 2017

Because of time-varying, nonlinearity and complexity of the machining process, the traditional PID control has been unable to meet the requirements, which are being high-speed and high-precision. However, an advanced control methods can be a good solution for this kind of control system, a prefect simulation results depends on the accuracy of the modeling process, such models can be used to develop more precise and formalized description of process activities, on modeling process, and now a days a lot of software had been used do this issue. This paper aims to create a milling machine process model using the Simulink modeling method, which use the logic of cutting process as a mathematical terms indicates areal milling machining equations, and give it appropriate processing parameters to ensure the simulating results are comparable, the step response method will be used as good indicator to compare the Model process, using Matlab analysis, first the process will be modelled in the Matlab software to test the step response under various parameters and then compare the results.
Experimental research on influence of ground vibration on gun measurement instrument support
Authors: Wang Baoyuan , Guo Min , Hu Ming , Liu Jun , Du Wenbin
Published: October 2017

In order to know well the vibration law on influence of ground vibration on instrument support in gun firing process, a measuring method for the vibration response of the instrument support based on the principle of acceleration measurement is presented. The instrument support is arranged on the ground. When the gun fires, the acceleration response of the instrument support is measured. The vibration velocity and vibration displacement responses of the support can be obtained by the integral operation of the acceleration. The results show that when the gun fires with single shot and the period of the projectile in-bore motion, the vibration response of the instrument support caused by ground vibration is very small, and it can be ignored. When the projectile moves outside the bore, the ground vibration has a significant influence on the vibration of the instrument support. The vibration response of the instrument support in the range of muzzle shock wave is mainly caused by the muzzle shock wave.
Numerical simulation analysis of large eddy simulation for T-tube based on solid-liquid two-phase abrasive flow
Authors: Li Jun Ye , Meng Wen Qing , Zang Xiang , Zhang Xin Ming
Published: October 2017

As a kind of nano machining technology, abrasive flow polishing technology plays an important role in precision machining region. As an important numerical simulation method in fluid mechanics, large eddy numerical simulation method has become an important method for many scholars to study abrasive grain polishing technology. In this paper, the use of fluid mechanics software FLUENT and selected Mixture mixed model. Based on the theory of solid-liquid two-phase flow dynamics, the large-eddy numerical simulation method was used to study the polishing process of T-tube abrasive flow, and the micro-machining mechanism of abrasive-polished workpiece was discussed. The influence of the different inlet velocities on the polishing effect of the abrasive grains was discussed by analyzing the numerical simulation results of the different inlet velocities of the abrasive grains during the processing of the T-tube.
A new type of high frequency mechanical vibration table
Authors: Gao Jin , Li Chaowei , Wang Dongying , Du Wenbin , Li Shili , Lei Qiang
Published: October 2017

This paper puts forward a new type of mechanical vibration table. First of all, the structure and working principle of this vibration table is described. Then the kinetic equation and the three-dimensional model of the eccentric exciter are established, the simulation experiments are carried out, and the displacement curves, velocity curves and acceleration time curves at different frequencies are analyzed. Finally, finite element analysis of eccentric wheels is carried out based on solidwork2012. The simulation results show that the mechanical vibration of this new mechanical vibration table is achievable at 0-100 Hz.
High frequency large stroke design and simulation experimental research on shaking table
Authors: Gao Jin , Li Chaowei , Wang Dongying , Du Wenbin , Li Shili , Lei Qiang
Published: October 2017

Firstly, this paper introduces the design of high frequency large stroke vibration table according to the applicable environment. Secondly, the three-dimensional solid model is established which is based on solidworks2012 environment. The kinematics and dynamics simulation of the shaking table model are carried out. The vibration test curve of the vibrating table is obtained, and the reason of the change of the vibration curve under different vibration frequency is analyzed. Finally, this paper concludes that this exciting scheme is feasible and effective.
Study on dynamic characteristics of double cylinder double acting bilge pump transmission
Authors: Xia Jiangmin , Li Zhuying , Zhang Zhenhai , Wei Guodong
Published: October 2017

In view of the complex structure of the ship bilge pump, the excitation source in the process of work is difficult to accurately determine the fault condition of the bilge pump through the vibration test data. Based on the theory of multi - body dynamics, rotor dynamics and electrical mechanics, the kinematics and kinetic equations of the bilge pump drive are established, and the dynamics, kinematics and vibration characteristics of bottom Pump drive analysis of the cabin is carried out. The frequency of the excitation force corresponding to the transmission mechanism is deduced, and the frequency of the excitation force of the main transmission is calculated.
Equivalent method for frequency division of complicated impact signal
Authors: Guo Min , Cao Xin , Li Chaowei , Gao Rui , Li Shili , Du Wenbin
Published: October 2017

This article describes a method of frequency division equivalent for complicated impact signal. In the complex impact signal analysis and processing, instantaneous frequency often plays an important role, the instantaneous frequency represents the position of the frequency peak with time, complicated impact signal has their instantaneous frequencies at some point. The method first calculates the power spectrum of the original signal, then the power spectral curve is integrated, the mean square value curve of the whole frequency band is obtained, the frequency amplitude curve can be obtained by square of mean square curve. According to the 1 kHz bandwidth, equal intervals are segmented to the frequency axis, the total root mean square values of each frequency band are calculated respectively, the ratio of each component to the total root mean square value of the whole frequency band is the contribution rate of the frequency band to the whole signal amplitude.
A new model for calculating time-varying gearmesh stiffness
Authors: Lei Yaguo , Wang Delong , Liu Zongyao , Yang Xiao
Published: October 2017

Time-varying gearmesh stiffness (TVGS) is the main cause of gear vibration, and its accuracy affects the responses of dynamic models. An exponential curve model based on the Saint Venant’s Principle is proposed to calculate the gearmesh stiffness of cracked spur gears in this paper. With the proposed model, the TVGS under the circumstances of healthy condition and four crack cases are computed, whose results have a good agreement with those of finite element method (FEM). Therefore, the exponential curve model can be used to estimate the TVGS and an alternative to FEM in gearmesh stiffness calculation is provided.
Direct and inverse problems on free vibration analysis of cracked non-uniform beams carrying spring-mass systems by finite element method
Authors: Tan Guojin , Liu Ziyu , Shan Jinghui , Wu Chunli
Published: October 2017

This paper presents an analytical approach to investigate the free vibration analysis of cracked non-uniform beam carrying spring-mass systems by finite element method and illustrates a valid and reliable damage identification method which using hybrid neural genetic technique. Firstly, based on the finite element method, the dynamic characteristics of non-uniform cracked beam carrying spring-mass systems are obtained. Then, the first five frequencies are used as input parameters by combining genetic algorithm with neural network to identify the damage. Finally, Numerical simulations of direct and inverse problems of non-uniform cracked beams carrying a spring-mass system are carried out.
Numerical calculation of wing-bending moment with real-time strain monitoring by FBG modulation
Authors: Zhang Weifang , Wei Wei , Jin Bo , Liang Xiaobei , Zhang Meng
Published: October 2017

This paper presents an application of Structural Health Monitoring System based on Fiber Bragg Grating sensors (FBGs) dedicated to wing-bending moment. A numerical calculation of bending moment is proposed to the application of real-time wing-bending moment monitoring. With the advantage of anti-electromagnetic interference, small size and light weight, Fiber Bragg grating (FBG) sensors have been applied in structural health monitoring system (SHMS). An experiment was performed in full-scale fatigue test of an aircraft, and the wings of aircraft were subjected to specific loading conditions, and the strain data was collected by FBGs’ demodulation. The relationship matrix K between the strain and the wing-bending moment was established. It is a new approach for the wing-bending moment real-time monitoring with the simple FBG strain collection modulation.
Flow-induced vibration in the compressible cavity flow
Authors: Li Hao , Tan Jianguo , Hou Juwei
Published: October 2017

The cavity plays an important role in the fuel-air mixing and combustion stability inside the hypersonic scramjet. However, the high levels of time-dependent loading resulting from the supersonic cavity flow can cause intense structural vibration even damage. Experiments and numerical simulations were performed to understand the complex fluid-structure interaction in this paper. A cantilever plate with a cavity was installed as a splitter plate in the supersonic mixing layer wind tunnel. The response displacements of this cantilever plate were measured by a non-intrusive laser vibrometer. Large eddy simulation (LES) was applied to calculate the aerodynamic loading. Results show that the St number of time-dependent surface-averaged pressure difference agrees well with semi-empirical relation of Heller used to predict the resonance mode. The cantilever plate exhibits a directly dependent response to self-oscillation of supersonic cavity flow. Measurement results of displacement indicate that the vibration shape of this plate is dominantly two-dimensional.
The application of improved signal summing method into the spacecraft force limited vibration test
Authors: Qiu Hanping , Liu Zhaoyan , Liang Xiaohua , Yue Zhiyong , Zhang Jungang , Fan Shichao , Feng Yaoqi , Sun Tong
Published: October 2017

This paper provides an improved signal summing method for the spacecraft force limited vibration test system with eight force transducers. The key point for this method is to change the combination way of the signals coming out of the eight force transducers while the formulas inside the signal conditioning amplifier have been used skillfully. This method had been successfully adopted in the spacecraft force limited vibration test and the accuracy requirements of key force and moment signals have been met. And this method has been proved to be a very powerful tool for providing the critical force and moment data used to determine the force limited profile during the spacecraft dynamic test.
Study on perception threshold for whole-body vibration
Authors: Liu Qiang , Kang Zhongxu , Song Ruixiang , Zhang Lijuan , Wu Qiong
Published: October 2017

When people stay in the vibrating environment for a long time, the body may produce a series of physiological and psychological diseases. In order to evaluate the impact of vibration on the human body, the establishment of evaluation method or evaluation system is necessary. At present, most countries usually evaluate whole-body vibration based on the international standard ISO 2631-1 “Mechanical vibration and shock-Evaluation of human exposure to whole-body vibration-Part 1: General requirements”. In this paper, the experiments of perception threshold of whole-body vibration were taken as the breakthrough point of evaluation method, and 12 subjects participated in the experiments. Through the experiments, comparing the provisions of ISO 2631-1, we get some different conclusions about the distribution law of perception thresholds. This also provides some data support for further experimental research.
Design and study of DC excitation power controller of superconductor fault current limiter
Authors: Li Hui
Published: October 2017

This paper provides a theoretical basis for high voltage magnetization and low voltage constant current excitation. The design structure of DC excitation power supply is put forward. As a controlled rectifier device, the 6RA70 is the core control unit of the superconducting fault current limiter. The problem that DC excitation power supply is difficult to control under high voltage and large current is effectively solved. The requirements of high voltage magnetization and constant current excitation control are expounded, and the switching methods between two states are described. PLC is used to establish a digital control system for networks. This paper provides a reference for the operation of superconducting fault current limiter.
Simulation on propagation characters of ground vibration induced by in-tunnel excitation source
Authors: Wu Qiong , Qu Yang , Zhang Hougui
Published: October 2017

In order to find the possibility of setting vibration mitigation measures at the transmission path for in-tunnel excitation source, a numerical calculation model of the tunnel and foundation was constructed. Using measurement vibration as the in-put excitation load, ground vibration propagation characters were calculated in cases of setting two common used vibration isolation measures, including open trench and buried concrete wall barrier. Calculation results indicated the open trench and buried concrete wall barrier can ideally shield the propagation of vibration induced by in-tunnel excitation source.
Application of ultrasonic guided waves for non-destructive testing of large and complex geometry engineering structures
Authors: Raišutis Renaldas , Kažys Rymantas , Mažeika Liudas , Žukauskas Egidijus , Šliteris Reimondas , Vladišauskas Alfonsas
Published: October 2017

The wide group of large engineering constructions made from welded metal components and modern composite materials during daily exploitation under non-stationary loads, continuous influence of vibrations and complicated environmental conditions have demand of periodical tests in order to avoid appearance and evolution of the defects. All of them have one common feature – large areas to be tested and the complex geometry. The objective is to improve air-coupled and contact type testing techniques for excitation and reception of appropriate modes of ultrasonic guided waves in large and complex structures. Also, to develop inspection techniques which enable to detect required types of internal defects. The air-coupled and contact ultrasonic techniques for investigation of large and complex geometry objects, such as composites for aerospace applications and petroleum tanks, have been developed. The investigation of propagation effects of ultrasonic guided (Lamb) waves in the plates of the tank floor has indicated relation between reconstructed properties of guided waves and expected presence of corrosion deposits.
Bearing fault diagnosis based on intrinsic time-scale decomposition and extreme learning machine
Authors: Wang Fei , Zhang Wenjin , Ding Yu
Published: October 2017

Fault diagnosis for bearings is a focus and difficulty in diagnosis research area, so an intelligent diagnosis method using intrinsic time-scale decomposition(ITD) and extreme learning machine (ELM) is proposed in this paper. ITD is a relatively practical non-stationary signal decomposition method, which can decompose non-stationary signal into several components. Then, coefficient of kurtosis was extracted, which was acquired to reduce feature dimensions. Last, in order to reduce man-made interference and increase diagnostic accuracy, ELM was applied to identify and classify bearing states. The experimental result shown that above methods work well in classification and diagnosis for bearings state timely.
A two-step approach for damage detection in beam based on influence line and bird mating optimizer
Authors: Tan Dong , Lu Zhong Rong
Published: October 2017

This paper presents a two-step approach for structural damage identification in beam structure using the influence line and bird mating optimizer (BMO). Local damage is simulated as the reduction of the elemental Young’s modulus and mass of beam element. The technique for damage localization based on influence line and its derivatives before and after damage for beam structure was outlined. An objective function comprised of dynamic acceleration is utilized for BMO algorithm. The dynamic response data under external force is calculated by Newmark integration method. Numerical examples of a simply supported beam was investigated. Effect of measurement noise is studied. Studies in the paper indicate that the proposed method is efficient and robust for identifying damages in beam structures.
Experimental approach for optical registration of circular time-averaged moiré images
Authors: Lu Guangqing , Maskeliunas Rimas , Aleksiene Sandra , Peng Wenbin
Published: October 2017

This paper presents the development of an experimental stand for the registration of time-averaged geometric circular moiré images. Optical interpretation of patterns of time-averaged moiré fringes allows to identify the parameters of circularly vibrating structures. The developed scheme has a strong potential for designing experimental schemes capable to measure angular vibrations of rotating shafts in different mechanisms, and do not require any mountable sensors.
A stochastic surrogate model for time-variant reliability analysis of flexible multibody system
Authors: Kan Linjie , Zhang Jianguo , Wang Qian
Published: October 2017

The dynamic model of the flexible multibody systems (FMS) is usually the differential equations with time-variant, high nonlinear and strong coupling characteristics. The traditional reliability models are inefficient to solve these problems. And the reliability model is poor in accuracy and computational efficiency. Based on this point, a new stochastic surrogate model for time-variant reliability analysis of FMS is proposed. Combined model order reduction with generalized polynomial chaos, the stochastic surrogate model is established and the statistical characteristics of system responses are obtained. The calculation method of kinematic time-variant reliability is given. Finally, the effectiveness of the method is verified by a rotating flexible beam. The results show that this method has high computational accuracy compared with Monte Carlo method.
Fault diagnosis of electro-mechanical actuator based on WPD-STFT time-frequency entropy and PNN
Authors: Jing Jiayao , Liu Hongmei , Lu Chen
Published: October 2017

Electro-mechanical actuators (EMAs) are increasingly being used as critical actuation devices of the aircraft. It will cause serious accidents once the fault of EMAs occurs, thus the fault diagnosis of EMAs is essential to maintain the normal operation of aircraft. In this paper, a method based on WPD-STFT time-frequency entropy and PNN is proposed to achieve fault diagnosis of EMAs by processing the vibration signals collected by the accelerometer installed in the EMAs. Firstly, the vibration signals are decomposed by wavelet packet to obtain the signal components of different frequency bands, the signal components are subjected to STFT and spectrograms are obtained. Then, time-frequency entropy is calculated and combined with principal component analysis (PCA) for dimension reduction as the feature vector. Finally, the probabilistic neural network (PNN) classifier is introduced to classify the fault modes. The experimental result shows that this method can accomplish the accurate fault diagnosis of EMAs. Moreover, the performance of the proposed WPD-STFT time-frequency entropy method has an advantage over that of WPD-PCA method or STFT combined with mass-moment entropy method for feature extraction.
Batch and fixed-bed column study for p-nitrophenol, methylene blue, and U(VI) removal by polyvinyl alcohol–graphene oxide macroporous hydrogel bead
Authors: Chen Dan , Zhou Jun , Wang Hongyu , Yang Kai
Published: October 2017

There is an increasing need to explore effective and clean approaches for hazardous contamination removal from wastewaters. In this work, a novel bead adsorbent, polyvinyl alcohol–graphene oxide (PVA-GO) macroporous hydrogel bead was prepared as filter media for p-nitrophenol (PNP), dye methylene blue (MB), and heavy metal U(VI) removal from aqueous solution. Batch and fixed-bed column experiments were carried out to evaluate the adsorption capacities of PNP, MB, and U(VI) on this bead. From batch experiments, the maximum adsorption capacities of PNP, MB, and U(VI) reached 347.87, 422.90, and 327.55 mg/g. From the fixed-bed column experiments, the adsorption capacities of PNP, MB, and U(VI) decreased with initial concentration increasing from 100 to 400 mg/L. The adsorption capacities of PNP, MB, and U(VI) decreased with increasing flow rate. Also, the maximum adsorption capacity of PNP decreased as pH increased from 3 to 9, while MB and U(VI) presented opposite tendencies. Furthermore, the bed depth service Time (BDST) model showed good linear relationships for the three ions' adsorption processes in this fixed-bed column, which indicated that the BDST model effectively evaluated and optimized the adsorption process of PVA-GO macroporous hydrogel bead in fixed-bed columns for hazardous contaminant removal from wastewaters.
THE STUDY OF EXPECTATION AND SATISFACTION OF D.EL.ED. STUDENTS WITH THEIR TEACHER
Authors: Rathod Jagdish B.
Published: October 2017

The expectation is a tendency which is of enervated by one individual towards another individual it is a mantel state of man in which he believed strongly to occur some behavior ministration and change by him self. The educational system becomes more perfect through researched concept of student centered education in a most revolution any change in the field the expectations and satisfaction of D.El.Ed student is depends on the following points that is the teacher behavior teaching process curriculum school The Positives of communication between teacher and student is based on relationship between them and relationship depends on the satisfaction or fulfillment of expectation. Keywords : D.El.Ed Student Expectation and Satisfaction with their teacher
The Effects of Restatements for Misreporting on Auditor Scrutiny of Peer Firms
Authors: Guo Feng , Kubick Thomas R. , Masli Adi
Published: October 2017

SYNOPSIS

Prior research contends that financial misreporting has a spillover effect on the outcomes of peer firms within the same industry through investment decisions, information risk, and shareholder wealth. We predict and confirm a higher level of audit fees for peer firms when serious misreporting by other firms is announced in the industry. We find this effect is limited to peers that exhibit poor internal control quality. In addition, we observe higher audit fees for peers of industry prominent misreporting firms and for peers of firms announcing restatements with larger negative market reactions. Overall, our results suggest that financial misreporting in the industry has a spillover effect on audit fees of non-misreporting peer firms.

Data Availability: All data are from public sources identified in the manuscript.