In this paper, a dynamic investigation is done for strip, rectangular and square machine foundation at the top surface of two-layer dry sand with various states (i.e., loose on medium sand and dense on medium sand). The dynamic investigation is performed numerically using finite element programming, PLAXIS 3D. The soil is expected as a versatile totally plastic material that complies with the Mohr-Coulomb yield criterion. A harmonic load is applied at the base with an amplitude of 6 kPa at a frequency of (2 and 6) Hz, and seismic is applied with acceleration – time input of earthquake hit Halabjah city north of Iraq. A parametric study is done to evaluate the influence of changing L/B ratio (Length=12,6,3 m and width=3 m), type of sand, and frequency of the machine for soil with two layers (dense and medium sand) and (loose and medium sand). It was noticed that the displacement decreases when the foundation is strip, and has the highest values when the foundation is square. At the same time, the maximum vertical stress of the foundation (L/B = 4 and L/B = 1) appears to be (1262) kPa and (1255) kPa, respectively, due to increasing the foundation mass as a result of increasing its dimensions. Then again, the displacement increases by 20% for vertical displacement when decreasing the relative density. In addition, it has been noticed that there is a decrease in displacement when the frequency value changes from (2 to 6) Hz.
Abstract
This paper represents a study of the effect of the soil type, the drilling parameters and the drilling tool properties on the dynamic vibrational behavior of the drilling rig and its assessment in the drilling system. So first, an experimental drilling rig was designed and constructed to embrace the numerical work.
The experimental work included implementation of the drill-string in different types of soil with different properties according to the difference in the grains size, at different rotational speeds (RPM), and different weights on bit (WOB) (Thrust force), in a way that allows establishing the charts that correlate the vibration acceleration, the rate of penetration (ROP), and the power
... Show MoreThis paper discusses using H2 and H∞ robust control approaches for designing control systems. These approaches are applied to elementary control system designs, and their respective implementation and pros and cons are introduced. The H∞ control synthesis mainly enforces closed-loop stability, covering some physical constraints and limitations. While noise rejection and disturbance attenuation are more naturally expressed in performance optimization, which can represent the H2 control synthesis problem. The paper also applies these two methodologies to multi-plant systems to study the stability and performance of the designed controllers. Simulation results show that the H2 controller tracks a desirable cl
... Show MoreA linear engine generator with a compact double-acting free piston mechanism allows for full integration of the combustion engine and generator, which provides an alternative chemical-to-electrical energy converter with a higher volumetric power density for the electrification of automobiles, trains, and ships. This paper aims to analyse the performance of the integrated engine with alternative permanent magnet linear tubular electrical machine topologies using a coupled dynamic model in Siemens Simcenter software. Two types of alternative generator configurations are compared, namely long translator-short stator and short translator-long stator linear machines. The dynamic models of the linear engine and linear generator, validated
... Show MoreWhen the guard honey bees, Apis mellifera L., form a clump at the hive entrance or on the flight board, the oriental hornet, Vespa orientails L., either creeps toward the clump or hovers over it in order to take a bee. Once the hornet creeps, only few bees facing the hornet become alert, rock their heads and antennae, open their wings, and take a posture of defense. The rest of the clump stays listless without any signal of concern. However, the clump stays dense and the defending bees do not detach themselves neither from the rest of the clump nor from each other. For this reason, it is very difficult for the hornet to grab a bee unless the latter makes a “mistake” by detaching herself from other adjacent bees. If the hornet grabs s
... Show MoreBackgroundCarcinoma of the larynx represent 10% of head & neck malignancies. The treatment of advanced carcinoma of larynx may include partial or total laryngectomy, with or without laser , radiotherapy,and or chemotherapy . Carcinoma of the larynx usually affect old age , heavy smoker with possible risk of pulmonary diseases & ischemic heart disease , which add risk to the general anaesthetic complication operative & postoperative - Objectives this study was designed to assess the feasibility of total laryngectomy under local anaesthesia in medically unfit patients for general anaesthesia & to re-establish practice doing total laryngectomy under local anaesthesia in those patients.
Methods a prospective study on 12 pa
The interim administration is an application of the idea of management required by certain circumstances, which are necessary and urgent, and most laws, especially the laws we have compared (the French Civil Code and the Egyptian civil law and the Iraqi civil law) did not regulate the idea of interim administration accurately, This idea is interrelated, but this idea is highlighted whenever a temporary administrator is needed. It is often necessary to maintain a financial or financial burden that is impossible for the owner to manage his own money for one reason or another, the appointment of a temporary manager who manages these funds, we find the legislator resort in such a case to appoint a manager to temporarily save and ma
... Show MoreBackgroundCarcinoma of the larynx represent 10% of head & neck malignancies. The treatment of advanced carcinoma of larynx may include partial or total laryngectomy, with or without laser , radiotherapy,and or chemotherapy . Carcinoma of the larynx usually affect old age , heavy smoker with possible risk of pulmonary diseases & ischemic heart disease , which add risk to the general anaesthetic complication operative & postoperative - Objectives this study was designed to assess the feasibility of total laryngectomy under local anaesthesia in medically unfit patients for general anaesthesia & to re-establish practice doing total laryngectomy under local anaesthesia in those patients.
Methods a prospective study on 12 pa
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