WAVE HEIGHT DISTRIBUTION FOR SPILLING WAVES IN THE SURF ZONE

TAO YOU,ZIDAN ZHAO,FANGPING ZHONG,ZUZHI WANG 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

A hybrid MC-HS model for 3D analysis of tunnelling under piled structures

Zidan, Ahmed F.,Ramadan, Osman M. Techno-Press 2018 Geomechanics & engineering Vol.14 No.5

In this paper, a comparative study of the effects of soil modelling on the interaction between tunnelling in soft soil and adjacent piled structure is presented. Several three-dimensional finite element analyses are performed to study the deformation of pile caps and piles as well as tunnel internal forces during the construction of an underground tunnel. The soil is modelled by two material models: the simple, yet approximate Mohr Coulomb (MC) yield criterion; and the complex, but reasonable hardening soil (HS) model with hyperbolic relation between stress and strain. For the former model, two different values of the soil stiffness modulus ($E_{50}$ or $E_{ur}$) as well as two profiles of stiffness variation with depth (constant and linearly increasing) were used in attempts to improve its prediction. As these four attempts did not succeed, a hybrid representation in which the hardening soil is used for soil located at the highly-strained zones while the Mohr Coulomb model is utilized elsewhere was investigated. This hybrid representation, which is a compromise between rigorous and simple solutions yielded results that compare well with those of the hardening soil model. The compared results include pile cap movements, pile deformation, and tunnel internal forces. Problem symmetry is utilized and, therefore, one symmetric half of the soil medium, the tunnel boring machine, the face pressure, the final tunnel lining, the pile caps, and the piles are modelled in several construction phases.

Dynamic Thermal Rating of Transmission Line Based on Environmental Parameter Estimation

Zidan Sun,Zhijie Yan,Likai Liang,Ran Wei,Wei Wang 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.2

The transmission capacity of transmission lines is affected by environmental parameters such as ambienttemperature, wind speed, wind direction and so on. The environmental parameters can be measured by theinstalled measuring devices. However, it is impossible to install the environmental measuring devicesthroughout the line, especially considering economic cost of power grid. Taking into account the limitednumber of measuring devices and the distribution characteristics of environment parameters and transmissionlines, this paper first studies the environmental parameter estimating method of inverse distance weightedinterpolation and ordinary Kriging interpolation. Dynamic thermal rating of transmission lines based on IEEEstandard and CIGRE standard thermal equivalent equation is researched and the key parameters that affect theload capacity of overhead lines is identified. Finally, the distributed thermal rating of transmission line isrealized by using the data obtained from China meteorological data network. The cost of the environmentalmeasurement device is reduced, and the accuracy of dynamic rating is improved.

Retroperitoneal Extrapleural Approach for Corpectomy of the First Lumbar Vertebra : Technique and Outcome

Zidan, Ihab,Khedr, Wael,Fayed, Ahmed Abdelaziz,Farhoud, Ahmed The Korean Neurosurgical Society 2019 Journal of Korean neurosurgical society Vol.62 No.1

Objective : Corpectomy of the first lumbar vertebra (L1) for the management of different L1 pathologies can be performed using either an anterior or posterior approach. The aim of this study was to evaluate the usefulness of a retroperitoneal extrapleural approach through the twelfth rib for performing L1 corpectomy. Methods : Thirty consecutive patients underwent L1 corpectomy between 2010 and 2016. The retroperitoneal extrapleural approach through the 12th rib was used in all cases to perform single-stage anterior L1 corpectomy, reconstruction and anterior instrumentation, except for in two recurrent cases in which posterior fixation was added. Visual analogue scale (VAS) was used for pain intensity measurement and ASIA impairment scale for neurological assessment. The mean follow-up period was 14.5 months. Results : The sample included 18 males and 12 females, and the mean age was 40.3 years. Twenty patients (67%) had sensory or motor deficits before the surgery. The pathologies encountered included traumatic fracture in 12 cases, osteoporotic fracture in four cases, tumor in eight cases and spinal infection in the remaining six cases. The surgeries were performed from the left side, except in two cases. There was significant improvement of back pain and radicular pain as recorded by VAS. One patient exhibited postoperative neurological deterioration due to bone graft dislodgement. All patients with deficits at least partially improved after the surgery. During the follow-up, no hardware failures or losses of correction were detected. Conclusion : The retroperitoneal extrapleural approach through the 12th rib is a feasible approach for L1 corpectomy that can combine adequate decompression of the dural sac with effective biomechanical restoration of the compromised anterior loadbearing column. It is associated with less pulmonary complication, no need for chest tube, no abdominal distention and rapid recovery compared with other approaches.

Multilevel Percutaneous Vertebroplasty (More than Three Levels) in the Management of Osteoporotic Fractures

Zidan, Ihab,Fayed, Ahmed Abdelaziz,Elwany, Amr The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.6

Objective : Percutaneous vertebroplasty (PV) is a minimally invasive procedure designed to treat various spinal pathologies. The maximum number of levels to be injected at one setting is still debatable. This study was done to evaluate the usefulness and safety of multilevel PV (more than three vertebrae) in management of osteoporotic fractures. Methods : This prospective study was carried out on consecutive 40 patients with osteoporotic fractures who had been operated for multilevel PV (more than three levels). There were 28 females and 12 males and their ages ranged from 60 to 85 years with mean age of 72.5 years. We had injected 194 vertebrae in those 40 patients (four levels in 16 patients, five levels in 14 patients, and six levels in 10 patients). Visual analogue scale (VAS) was used for pain intensity measurement and plain X-ray films and computed tomography scan were used for radiological assessment. The mean follow-up period was 21.7 months (range, 12-40). Results : Asymptomatic bone cement leakage has occurred in 12 patients (30%) in the present study. Symptomatic pulmonary embolism was observed in one patient. Significant improvement of pain was recorded immediate postoperative in 36 patients (90%). Conclusion : Multilevel PV for the treatment of osteoporotic fractures is a safe and successful procedure that can significantly reduce pain and improve patient's condition without a significant morbidity. It is considered a cost effective procedure allowing a rapid restoration of patient mobility.

Electromagnetic Environment of Transmission Line Based on Full Parameter Online Estimation

Zidan Sun,Xiaofeng Zhou,Likai Liang,Yang Mo 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.2

The parameters of transmission lines have an influence on the electromagnetic environment surrounding theline. This paper proposes a method based on phasor measurement unit (PMU) and supervisory control and dataacquisition (SCADA) to achieve online estimation of transmission line full parameters, such as resistance,reactance and susceptance. The proposed full parameter estimation method is compared with the traditionalmethod of estimating resistance independently based on SCADA system. Then, the electromagnetic environmentis analyzed based on the different parameter estimation methods. The example results illustrate that onlineestimation of transmission line full parameters is more accurate in the analysis of electromagnetic environment,which further confirms its necessity and significance in engineering application.

Magnetization Behavior and Magnetic Entropy Change on FeZrMn Alloys

J. Zidanic,K.S. Kim,S.G. Min,K.Y. Kim,S. C. Yu 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Dynamic Thermal Rating of Transmission Line Based on Environmental Parameter Estimation

Sun, Zidan,Yan, Zhijie,Liang, Likai,Wei, Ran,Wang, Wei Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.2

The transmission capacity of transmission lines is affected by environmental parameters such as ambient temperature, wind speed, wind direction and so on. The environmental parameters can be measured by the installed measuring devices. However, it is impossible to install the environmental measuring devices throughout the line, especially considering economic cost of power grid. Taking into account the limited number of measuring devices and the distribution characteristics of environment parameters and transmission lines, this paper first studies the environmental parameter estimating method of inverse distance weighted interpolation and ordinary Kriging interpolation. Dynamic thermal rating of transmission lines based on IEEE standard and CIGRE standard thermal equivalent equation is researched and the key parameters that affect the load capacity of overhead lines is identified. Finally, the distributed thermal rating of transmission line is realized by using the data obtained from China meteorological data network. The cost of the environmental measurement device is reduced, and the accuracy of dynamic rating is improved.

Three Dimensional Numerical Analysis of the Effects of Tunnelling Near Piled Structures

A. F. Zidan,O. M. O. Ramadan 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4

The construction of tunnels in soft ground leads to ground movements. In urban areas with soft soils, these movements can affect the safety of surface structures. This paper investigates the interaction between tunnelling in soft soil and adjacent piled structure. Several three-dimensional finite element analyses are performed to study the deformation of pile caps and piles during the construction of a nearby tunnel. Comparison between free field and coupled analyses is also presented. To simulate the tunnelling process and its effects on piled structures, one symmetric half of the soil medium, the tunnel boring machine, the face pressure, the final tunnel lining, the pile caps, and the piles are modelled in several construction phases. The first part of the paper describes the adopted numerical model. Then, pile cap movements as well as pile deformation and bending moments resulting from the tunnelling process are investigated. The influence of the superstructure stiffness and its gravity load level on the tunnelling-produced response of the pile foundation is also investigated. Finally, the results of coupled analyses, which include the superstructure, are compared to those obtained using the analysis of piles alone (excluding the superstructure). This comparison helps to evaluate the later type of analysis that is typically implemented in routine designs.

Substitution Eect of Ba in Sr2FeMoO6 Compounds for Magnetic-Entropy Change

유성조,민성기,Jerrome Zidanic,김경섭,김영석,이보화,김재영 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

The magnetization behaviors have been analyzed for double-perovskite Sr2-xBaxFeMoO6 (x = 0, 0.1, 0.2) compounds. The Curie temperature decreased from 391 K to 386 K with increasing Ba concentration. A large magnetic entropy change (ΔSM), which was calculated from the H versus M curves associated with the ferromagnetic-paramagnetic transitions, has been observed. The maximum ΔSM of Sr2FeMoO6 was 0.413 J/kg K at 391 K for an applied field of 1.5 T. With increasing Ba concentration, ΔSM decreased, being 0.399 and 0.405 J/kg K at 388 and 386 K (the Curie temperature), respectively.