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The interaction between rock mass structural planes and dynamic stress levels is important to determine the stability of rock mass structures in underground geotechnical engineering. In this work, the authors aim to focus on the degradation effects of fracture geometric parameters and unloading stress paths on rock mechanical properties.

A three-dimensional Particle Flow Code (PFC3D) was used for a systematic numerical simulation of the strength failure and cracking behavior of granite specimens containing prefabricated cracks under conventional triaxial compression and triaxial unilateral unloading. The authors demonstrated the unique mechanical response of prefabricated fractured rock under two conditions. The crack initiation, propagation, and coalescence process of pre-fissured specimens were analyzed in detail.

The authors show that the prefabricated cracks and unilateral unloading conditions not only deteriorate the mechanical strength but also have significant differences in failure modes. The degrading effect of cracks on model strength increases linearly with the decrease of the dip angle. Under the condition of true triaxial unilateral unloading, the deterioration effect of peak strength of rock is very significant, and unloading plays a role in promoting the instability failure of rock after peak, making the rock earlier instability failure. Associating with the particle vector diagram and crack coalescence process, the authors find that model failure mode under unilateral loading conditions is obviously distinct from that in triaxial loading. The peak strain in the unloading direction increases sharply, resulting in a new shear slip.

This study is expected to improve the understanding of the strength failure and cracking behavior of fractured rock under unilateral unloading.

The surface finish is an essential step in printed circuit boards design because it provides a solderable surface for electronic components. The purpose of this study to investigate the effects of different surface finishes during the soldering and ageing process.

The solder joints of Sn-4.0Ag-0.5Cu/Cu and Sn-4.0Ag-0.5Cu/electroless nickel/immersion silver (ENImAg) were investigated in terms of intermetallic (IMC) thickness, morphology and shear strength. The microstructure and compositions of solder joints are observed, and analyzed by using scanning electron microscopy (SEM-EDX) and optical microscope (OM).

Compounds of Cu₆Sn₅ and (Cu, Ni)₆Sn₅ IMC were formed in SAC405/Cu and SAC405/ENImAg, respectively, as-reflowed. When the sample was exposed to ageing, new layers of Cu₃Sn and (Ni, Cu)₃Sn₅ were observed at the interface. Analogous growth in the thickness of the IMC layer and increased grains size commensurate with ageing time. The results equally revealed an increase in shear strength of SAC405/ENImAg because of the thin layer of IMC and surface finish used compared to SAC405/Cu. Hence, a ductile fracture was observed at the bulk solder. Overall, the ENImAg surface finish showed excellent performance of solder joints than that of bare Cu.

The novel surface finish (ENImAg) has been developed and optimized. This alternative lead-free surface finish solved the challenges in electroless nickel/immersion gold and reduced cost without affecting the performance.

This study aims to theoretically contextualize the liquefied natural gas (LNG) issue using Bauman and Debord. More generally, this research provides a theoretical and qualitative context to understand the LNG issue in discussions of environmental management, globalization and local government.

This study uses Boje’s narrative case study approach to analyze the politics around localized resistance movements to LNG production in the Rio Grande Valley (RGV). Specifically, this study examines the data collected from the Federal Energy Regulatory Commission, personal interviews and public declarations (newspapers, blogs, social media) to create an historiographical account of LNGs in the RGV to analyze the Laguna Madre resistance case regarding three LNG companies.

The development of LNG in Laguna Madre has been at least temporarily halted. This is considered partially because of the pandemic, reduced demand and local resistance. In the Laguna Madre case, controlling narratives by the LNG resistance appeared to be an essential component of their overall strategy.

Understanding the impact of energy development locally and globally becomes increasingly important, as access to fossil fuels become more limited. This case helps understand the overall adverse actions taken by LNGs to exploit communities, individuals and the environment while illustrating practical tools being used to resist the less desirable elements of energy development.

The purpose of this paper is to explore and investigate the mechanical as well as bacterial characteristics of chemically treated waste natural fiber inserted three-dimensional structures (NFi3DS) produced with fused filament deposition (FFD) for biomedical applications.

In this work, a novel approach has been used for developing the customized porous structures particularly for scaffold applications. Initially, raw animal fibers were collected, and thereafter, the chemical treatment has been performed for making their wise utility in biomedical structures. For this purpose, silk fiber and sheep wool fibers were used as laminations, whereas polylactic acid was used as matrix material. A low-cost desktop time additive manufacturing setup was used for making the customized and porous parts by considering type of fiber, number of laminates, infill density and raster angle as input parameters.

The results obtained after using design of experimental technique highlighted that output characteristics (such as dimensional accuracy, hardness, three-point bending strength and bacterial test) are influenced by input parameters, as reported in the obtained signal/noise plots and analysis of variance. Optimum level of input parameters has also been found through Taguchi L9 orthogonal array, for single parametric optimization, and teaching learning-based algorithm and particle swarm optimization, for multiple parametric optimization. Overall, the results of the studies supported the use of embedded structures for scaffold-based biomedical applications.

Presently, NFi3DS were produced by using the hand-lay-based manual approach that affected the uniform insert’s distribution and thickness. It is advised to use the automatic fiber placement system, synced with a three-dimensional printer, to achieve greater geometrical precision.

As both natural fibers and polymer matrix used in this work are well established for their biological properties, hence the methodology explored in this work will help the practitioners/academicians in developing highly compatible scaffold structures.

The present work defines a new practice where the researchers can use natural fibers to reduce the cost associated with fabrication of customized scaffold prints.

The development of natural fiber embedded FFD-based structures is not yet explored for their feasibility in biomedical applications.

Polyoxyethylated hydroxy benzyl oleamide has found use in lubricants to prevent adhesion in moulds during the production of vulcanizates of natural and of synthetic rubbers. Polyoxyethylated oleamide acts as a mould lubricant for synthetic rubbers, whilst polyglycol 400 dilaurate can be used to reduce the time and temperature necessary for the recovery of old vulcanizates using paraffin oil and bitumen. Anti‐fogging properties can be sustained in rubber hydrochloride films by the use of polyglycol 1500 dilaurate, and improved percentage elongation can be promoted in intimate blends of polystyrene and SBR rubbers by the inclusion of polyglycol 4000 monostearate. Polyoxyethylated sorbitan monostearate acts as an emulsifer in the emulsion polymerisation of styrene, butadiene and styrene/ butadiene copolymer rubbers, and it can perform as an anti‐static for the latter. Polyoxyethylated stearylamine can be incorporated into lubricants designed to prevent adhesion in moulds during production of vulcanizates of synthetic and of natural rubber, and rubber latexes and other aqueous dispersions of rubber can be rendered more stable by the employment of polyoxyethylated stearyl alcohol, and thus allow storage in untreated containers for long periods of time. Polyoxypropylated sorbitan monopalmitate will serve as a parting agent, releasing aid, for unvulcanized rubber and vulcanized rubber, without interfering with further bonding and coating of rubber.

In the article, analytical model of first-order shear deformation (FSDT) beams made of jute–epoxy is presented to study the low-velocity impact response.

The nonlinear Hertz contact law is applied to identify the contact between projectile and beam. The energy method, Lagrange's equations and Ritz method are applied to derive the nonlinear governing equation of the beam and impactor-associated boundary condition. The motion equations are then solved simultaneously by the Runge–Kutta fourth-order method.

Also, a comparison is performed to validate the model predictions. The contact force and beam indentation histories of the jute–epoxy simply supported beam under spherical impactor with different radius and initial velocity are investigated in detail. It is found that in response to impactor radius increase, the utilization of the contact force law has resulted in a same increasing trend of peak contact force, impact duration and beam indentation, while in response to impactor initial velocity increase, the maximum contact force and beam indentation increase while impact time has vice versa trend.

This paper fulfills an identified need to study how jute–epoxy beam behavior with simply supported boundary conditions under low-velocity impact can be enabled.

The development of the Marcellus Shale Play has altered the geography of production in the USA, particularly in the Northeast natural gas market. The purpose of this paper is to examine its impact on an already integrated industry.

The authors utilize the methodology of co-integration and focus on the geographic reach of the Marcellus region to examine movements of prices across the upstream, midstream and downstream segments of the industry.

The results of this paper indicate that prices across segments remain strongly co-integrated with the boom in production. The short-run dynamics, however, reveal a slower adjustment to the long-run equilibrium following the boom, particularly for wellhead to city-gate and wellhead to residential prices.

The growth in delivery infrastructure has not kept up with the boom in production creating bottlenecks. The supply shock brought about by the boom in production has not altered previously established co-integrating relationships but has altered the speeds of adjustment towards the long-run equilibrium.

This paper aims at the problem of surrounding rock excavation damage zone of tunneling in the rich water region, this paper aims to propose a new seepage-stress-damage coupling model and studied the numerical algorithm. This reflects the characteristics of rock damage evolution, accompanied by plastic flow deformation and multi-field interaction.

First of all, rock elastoplastic damage constitutive model based on the Drucker–Prager criterion is established, the fully implicit return mapping algorithm is adopted to realize the numerical solution. Second, based on the relation between damage variation and permeability coefficient, the rock stress-seepage-damage model and multi-field coupling solving iterative method are presented. Finally, using the C++ language compiled the corresponding programs and simulated tunnel engineering in the rich water region.

Results show that difference evolution-based back analysis inversed damage parameters well, at the same time the established coupling model and calculating program have more advantages than general conventional methods. Multiple field coupling effects should be more considered for the design of tunnel support.

The proposed method provides an effective numerical simulation method for the construction of the tunnel and other geotechnical engineering involved underground water problems.

The purpose of this paper is to explore the relationship between big data and knowledge management (KM).

The study adopts a qualitative research methodology and a case study approach was followed by conducting nine semi-structured interviews with open-ended and probing questions.

Useful predictive knowledge can be generated through big data to help companies improve their KM capability and make effective decisions. Moreover, combination of tacit knowledge of relevant staff with explicit knowledge obtained from big data improvises the decision-making ability.

The focus of the study was on oil and gas sector, and, thus, the research results may lack generalizability.

This paper fulfills an identified need of exploring the relationship between big data and KM which has not been discussed much in the literature.

The purpose of this paper is to propose a novel quasi-nonlocal coupling of the bond-based peridynamic model with the classical continuum mechanics model to fully take advantage of their merits and be free of ghost forces.

This study reconstructs a total energy functional by introducing a coupling parameter that alters only the nonlocal interactions in the coupling region rather than the whole region and a modified elasticity tensor that affects the local interactions. Then, the consistency of force patch test is enforced in the coupling region to completely eliminate the ghost force in a general energy-based coupling scheme. For a one-dimensional problem, these coupling parameters are further determined through an energy patch test to preserve the energy equivalence or through an l¹-regularization. And, for a two- or three-dimensional problem, depending on the existence of a solution to the discretized force patch test, they are determined through an l¹-minimization or l¹-regularization.

One- and two-dimensional numerical examples under affine deformation have been conducted to verify the accuracy of the quasi-nonlocal coupling method, which exhibits no ghost force. Moreover, the coupling model can reproduce almost the same deformation behaviors of points near the crack for a cracked plate under tension as that from a pure peridynamic model, the former with a rather low computational cost and an easier application of boundary conditions.

This work is aiming at getting over long-standing ghost force issues in the energy-based coupling scheme. The numerical results from the cracked plate problem are exhibited promising extension to dynamic problems.