Investigation on the Performance of Partial Penetration Welds in Multicell Concrete Filled Steel Tubes

This paper presents an experimental and analytical investigation on the performance of partial penetration welds used to adjoin steel plates in irregular shaped multicell concrete filled steel tubes. The experimental program of this study is designed based on an actual implementation of such members as mega columns in a super high rise building in China. A total of six specimens are designed with different plate arrangements for the purpose of testing the performance of the partial penetration welds at different locations of the specimen. The designed specimens are tested under different load procedures and directions; this is achieved by placing them in vertical and slantwise manners between two loading plates which impose monotonic and cyclic actions. The failure conditions of each of the tested specimens are presented and discussed in detail and are based on the conclusions drawn from the experimental observations; the partial penetration weld at the corner of the tested specimens is found to be the most vulnerable. To facilitate large scale analysis, a finite element model constructed by the finite element analysis program ABAQUS is verified against experimental results. The evaluation of the stress at the partial penetration welded corner is carried out following an empirical procedure, which is adopted due to the complexity of the problem domain. The adopted procedure consists of two steps: the first one is to initially evaluate the stress based on an existing method in the literature, and the second one is to fit the results of the initial evaluation with the finite element model results based on parametric and regression analysis. After performing regression analysis, a formula to predict the weld stress is concluded, and the results of the proposed equation are found to be satisfactory when compared with the finite element model results.

Scaling of DD fusion power in a nanosecond vacuum discharge

Earlier, in a nanosecond vacuum discharge (NVD) with a deuterated Pd anode, the appearance of DD neutrons was observed not only at the well-studied quasi-stationary stage, where a virtual cathode (VC) appears in the interelectrode space, but also at the very initial stage of the discharge. An analysis of the experiment shows that the autoelectron beam can play the role of a kind of trigger for starting DD syntheses processes on the surface or in the bulk of the Pd anode, but its mechanism at the initial stage of the discharge remained unclear. In this work, we performed PiC modeling of the possible partial penetration of a beam of autoelectrons into hollow anode Pd tubes. This leads to the formation of very small short-lived VCs inside individual Pd tubes, where, starting from a current of 100 A, DD microsynthesis is possible. It is shown that in devices with oscillating ions the favorable scaling of the DD fusion power, which increases with decreasing VC radius, can be retained up to rVC  0.02 cm.

Quantifying the partial penetration skin factor for evaluating the completion efficiency of vertical oil wells

An oil well's productivity is generally considered the standard measure of the well's performance. However, productivity depends on several factors, including fluid characteristics, formation damage, the reservoir's formation, and the kind of completion the well undergoes. How a partial completion can affect a well's performance will be investigated in detail in this study, as nearly every vertical well is only partially completed as a result of gas cap or water coning issues. Partially penetrated wells typically experience a larger pressure drop of fluid flow caused by restricted regions, thus increasing the skin factor. A major challenge for engineers when developing completion designs or optimizing skin factor variables is devising and testing suitable partial penetration skin and comparing completion options. Several researchers have studied and calculated a partial penetration skin factor, but some of their results tend to be inaccurate and cause excessive errors. The present work proposes experimental work and a numerical simulation model for accurate estimation of the pseudo-skin factor for partially penetrated wells. The work developed a simple correlation for predicting the partial penetration skin factor for perforated vertical wells. The work also compared the results from available models that are widely accepted by the industry as a basis for gauging the accuracy of the new correlation in estimating the skin factor. Compared to other approaches, the novel correlation performs well by providing estimates for the partial penetration skin factor that are relatively close to those obtained by the tested models. This work's main contribution is the presentation of a novel correlation that simplifies the estimation of the partial penetration skin factor in partially completed vertical wells.

Distribution of Bacterial Contamination in Partial Penetration Surrogate Ballistic Wounds

With the rise in use of IEDs during armed conflicts, there has been an increase in the number of injuries to the extremities. Shrapnel and debris ejected during the explosion become high-speed projectiles capable of penetrating soft tissues, bringing bacterial contamination into the wound. If not properly treated, that contamination could lead to infection. Studies aimed at understanding the distribution of bacterial contamination along the permanent cavity could provide useful information to improve treatment protocols for these types of injuries. In this paper, a lower extremity surrogate model was used to investigate bacterial distribution in partial penetration ballistic wounds. The targets used were ballistic gelatin blocks that had an Escherichia coli-laden filter paper placed on their front face. Spherical projectiles were fired into the targets adjusting their speed to obtain three different partial penetration depths. After each shot, a gelatin strip containing the permanent cavity was extracted and segmented. The permanent cavity was removed from each segment, placed in a test tube with buffer solution, and heated in a water bath to melt the gelatin. Standard microbiology protocols were followed to determine the number of colony forming units (CFUs) in each segment. The bacteria distribution was represented by percent of total CFU in the permanent cavity versus segment number. In addition, bacterial contamination as a function of projectile penetration depth was explored. For the cases considered, most of the bacterial contamination occurred in the segments closer to the projectile entry point.