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Laser directed energy deposition (DED-LB) technology is currently facing challenges in controlling geometry accuracy of metal components. There is an urgent need to develop a numerical model that is more efficient and accurate compared to existing models and to analyze the dynamic behavior of the melt pool under the interaction of process parameters during DED-LB process to optimize parameters with fewer experimental studies to reduce costs. Therefore, a three-dimensional powder-scale multi-physics model is proposed during the single-track DED-LB process in this study. The powder particles are added by a Lagrangian particle model in this model without the need for assuming that the powder particles entering the molten pool are added by the mass source term, which improves model accuracy and efficiency. The effects of energy per unit mass (EUM, J g−1), mass per unit length (MUL, g mm−1), and standoff distance (SD, mm) intensities on transient molten pool motion and flow field are comprehensively investigated. It is discovered that the proposed model is able to predict the single-track height, width, depth, and dilution rate, or less than 9% relative error from experimentation, providing a useful tool for track geometry to predict. Furthermore, the flow velocity, width, and depth of melt pool also gradually are improved with higher EUM, MUL, and SD intensity and fluctuate within a small range. However, the height is improved and then decreases with higher SD intensity, and is improved with higher EUM or MUL. Overall, this study contributes to developing an optimizing process approach to improve formation accuracy for DED-LB manufacturing. [ABSTRACT FROM AUTHOR]

Highly efficient microwave absorbents and multilayer composite structures are crucial methods for enhancing electromagnetic wave (EMW) absorbent performance and broadening the bandwidth of materials. Herein, Ni-Fe/NBR microwave-absorbing composite sheets were prepared for the first time by uniformly dispersing Ni-Fe alloy fiber absorbers into a nitrile butadiene rubber (NBR) matrix using a mechanical mixing method. By varying the content and length of Ni-Fe fibers, thickness of Ni-Fe/NBR and blowing agent content (AC), a series of composites with low reflectivity and different frequency bands were obtained in the 2–18 GHz frequency. As a result, the single-layer NBR sheet with a Ni-Fe fiber content of 15% and fiber length of 3 mm can reach a minimum reflection loss (RLmin) of − 11.92 dB at a thickness of 2.7 mm. Secondly, it is noteworthy that double-layer stacked single-layer NBR absorbers can broaden the absorption bandwidth and improve the absorption effect. Furthermore, varying the positions of the upper and lower layers of sheet materials can yield disparate outcomes. The double-layer Ni-Fe/NBR absorber can achieve an RLmin of − 38.05 dB. Its effective absorption bandwidth (EAB) is 5.06 GHz in the C band and 3.44 GHz in the Ku band. This work provides new ideas for the design of efficient wave-absorbing flexible composites with structural functionalization. [ABSTRACT FROM AUTHOR]

Aiming to analyze the damage mechanism of UTAO from the perspective of meso-mechanical mechanism using discrete element method (DEM), we conducted study of diseases problems of UTAO in several provinces in China, and found that aggregate spalling was one of the main disease types of UTAO. A discrete element model of UTAO pavement structure was constructed to explore the meso-mechanical mechanism of UTAO damage under the influence of layer thickness, gradation, and bonding modulus. The experimental results show that, as the thickness of UTAO decreasing, the maximum value and the mean value of the contact force between all aggregate particles gradually increase, which leads to aggregates more prone to spalling. Compared with OGFC-5 UTAO, AC-5 UTAO presents smaller maximum and average values of all contact forces, and the loading pressure in AC-5 UTAO is fully diffused in the lateral direction. In addition, the increment of pavement modulus strengthens the overall force of aggregate particles inside UTAO, resulting in aggregate particles peeling off more easily. The increase of bonding modulus changes the position where the maximum value of the tangential force appears, whereas has no effect on the normal force. [ABSTRACT FROM AUTHOR]

Selenium constitutes an essential trace element for the human body. Moderate Se intake plays a pivotal role in preserving overall health. The absorption of Se by plants is primarily influenced by the available Se levels in soils, rather than by the soil total Se content, offering potential for exploring Se-rich crops in Se-deficient regions. In this study, we explore the factors influencing the Se bioaccumulation coefficient in corn based on a land quality geochemical survey at a 1:50,000 scale and establish predictive models for corn seed Se content using random forest and multiple linear regression approaches. The results indicate that the surface soil in the study area is deficient in Se (0.18–1.21 mg/kg), but 54% of the corn grain samples met the standards for Se-rich products (0.02–0.30 mg/kg). The factors influencing the Se biological enrichment coefficient in corn seeds are soil pH and CaO and MgO content, with impact levels of 0.54, 0.42, and 0.35, respectively. Compared to multiple linear regression models, the RF model provides more accurate and reliable predictions of corn Se content. The random forest model indicates that approximately 41% of the farmland within the study area is conducive to the cultivation of naturally Se-rich corn, which is a 26% increase in the planting area compared to recommendations based solely on soil Se content. In this research, we introduce an innovative methodological framework for organically cultivating naturally Se-rich corn within regions affected by Se deficiency. [ABSTRACT FROM AUTHOR]

The distribution characteristics of air voids in ultrathin asphalt friction course(UAFC) samples with different gradations and compaction methods were statistically analyzed using X-ray computed tomography (CT) and image analysis techniques. Based on the results, compared with the AC-5 sample, the OGFC-5 mixture has a higher air void ratio, a larger air void size and a greater number of air voids, with the distribution of internal air voids being more uniform and their shapes being more rounded. The two-parameter Weibull function was applied to fit the gradation of air voids. The fitting results is good, and the function parameters are sensitive to changes in both mineral gradation and compaction method. Moreover, two homogeneity indices were proposed to evaluate the compaction uniformity of UAFC samples. Compared with the Marshall method, the SGC method is more conducive to improve the compaction uniformity of UAFC samples. The compaction method significantly influences the air void distribution characteristics and compaction uniformity of AC-5 sample, but has a less significant impact on OGFC-5 sample. The experimental results in the study provides a solid foundation for further explorations on the internal structure and mixture design of UAFC. [ABSTRACT FROM AUTHOR]

The dynamics of a single cavitation bubble exposed to a transient acceleration is studied experimentally. A single cavitation bubble is seeded with a pulsed laser in a free-falling and impacting water-filled test tube. After impact, a pressure wave containing compression and rarefaction phases is generated and interacts with the bubble. The bubble dynamics is studied with high-speed imaging and compared to numerical simulations using the Keller–Miksis model. The timing of bubble seeding with respect to the pressure wave is varied, and a regime of enhanced collapse strength is found. [ABSTRACT FROM AUTHOR]

Smoothing Newton methods, which usually inherit local quadratic convergence rate, have been successfully applied to solve various mathematical programming problems. In this paper, we propose an accelerated smoothing Newton method (ASNM) for solving the weighted complementarity problem (wCP) by reformulating it as a system of nonlinear equations using a smoothing function. In spirit, when the iterates are close to the solution set of the nonlinear system, an additional approximate Newton step is computed by solving one of two possible linear systems formed by using previously calculated Jacobian information. When a Lipschitz continuous condition holds on the gradient of the smoothing function at two checking points, this additional approximate Newton step can be obtained with a much reduced computational cost. Hence, ASNM enjoys local cubic convergence rate but with computational cost only comparable to standard Newton's method at most iterations. Furthermore, a second-order nonmonotone line search is designed in ASNM to ensure global convergence. Our numerical experiments verify the local cubic convergence rate of ASNM and show that the acceleration techniques employed in ASNM can significantly improve the computational efficiency compared with some well-known benchmark smoothing Newton method. [ABSTRACT FROM AUTHOR]

The current-induced spin-orbit torque (SOT) is one of the most promising ways for high speed and low power spintronics devices. However, the mechanism of SOT driven magnetization reversal, especially the role of the field-like torque (FLT), is still unclear. Here, we report the observed promotion and suppression of switching by FLT, which depends on the relative direction of FLT and spin polarization. Our results reveal that the FLT could modulate the switching speed and power consumption by affecting the work done by the damping-like torque, and leads two different reversal dynamical paths during the switching. Furthermore, the origin of incubation time in SOT induced switching is clarified simultaneously. [ABSTRACT FROM AUTHOR]

In this paper, we study the linear convergence of several well-known first-order primal-dual methods for solving a class of convex-concave saddle point problems. We first unify the convergence analysis of these methods and prove the O(1/N) convergence rates of the primal-dual gap generated by these methods in the ergodic sense, where N counts the number of iterations. Under a mild calmness condition, we further establish the global Q-linear convergence rate of the distances between the iterates generated by these methods and the solution set, and show the R-linear rate of the iterates in the nonergodic sense. Moreover, we demonstrate that the matrix games, fused lasso and constrained TV- ℓ 2 image restoration models as application examples satisfy this calmness condition. Numerical experiments on fused lasso demonstrate the linear rates for these methods. [ABSTRACT FROM AUTHOR]

The Barzilai–Borwein (BB) gradient method is efficient for solving large-scale unconstrained problems to modest accuracy due to its ingenious stepsize which generally yields nonmonotone behavior. In this paper, we propose a new stepsize to accelerate the BB method by requiring finite termination for minimizing the two-dimensional strongly convex quadratic function. Based on this new stepsize, we develop an efficient gradient method for quadratic optimization which adaptively takes the nonmonotone BB stepsizes and certain monotone stepsizes. Two variants using retard stepsizes associated with the new stepsize are also presented. Numerical experiments show that our strategies of properly inserting monotone gradient steps into the nonmonotone BB method could significantly improve its performance and our new methods are competitive with the most successful gradient descent methods developed in the recent literature. [ABSTRACT FROM AUTHOR]

An inexact accelerated stochastic Alternating Direction Method of Multipliers (AS-ADMM) scheme is developed for solving structured separable convex optimization problems with linear constraints. The objective function is the sum of a possibly nonsmooth convex function and a smooth function which is an average of many component convex functions. Problems having this structure often arise in machine learning and data mining applications. AS-ADMM combines the ideas of both ADMM and the stochastic gradient methods using variance reduction techniques. One of the ADMM subproblems employs a linearization technique while a similar linearization could be introduced for the other subproblem. For a specified choice of the algorithm parameters, it is shown that the objective error and the constraint violation are O (1 / k) relative to the number of outer iterations k. Under a strong convexity assumption, the expected iterate error converges to zero linearly. A linearized variant of AS-ADMM and incremental sampling strategies are also discussed. Numerical experiments with both stochastic and deterministic ADMM algorithms show that AS-ADMM can be particularly effective for structured optimization arising in big data applications. [ABSTRACT FROM AUTHOR]

We consider the asymptotic behavior of a family of gradient methods, which include the steepest descent and minimal gradient methods as special instances. It is proved that each method in the family will asymptotically zigzag between two directions. Asymptotic convergence results of the objective value, gradient norm, and stepsize are presented as well. To accelerate the family of gradient methods, we further exploit spectral properties of stepsizes to break the zigzagging pattern. In particular, a new stepsize is derived by imposing finite termination on minimizing two-dimensional strictly convex quadratic function. It is shown that, for the general quadratic function, the proposed stepsize asymptotically converges to the reciprocal of the largest eigenvalue of the Hessian. Furthermore, based on this spectral property, we propose a periodic gradient method by incorporating the Barzilai-Borwein method. Numerical comparisons with some recent successful gradient methods show that our new method is very promising. [ABSTRACT FROM AUTHOR]

Conclusion: The effect of the MgO interlayer in the W/CoFeB interface on the charge-to-spin current conversion efficiency was experimentally investigated by changing the MgO interlayer thicknesses. Experimental results show high |ξdl| up to 0.58 by introducing a 0.22-nm-thick MgO interlayer, which is 45% enhanced as compared to the one without the MgO interlayer. The switching current density in the corresponding MTJs was also reduced by nearly 48% under 1-ns-width pulse tests. The improved switching efficiency can be explained by the enhanced Rashba effect at the W/MgO interface theoretically. In summary, these findings give potential solutions to the high-power dissipation issue for the tungsten-based SOT-MTJs. [ABSTRACT FROM AUTHOR]

In this paper, we study a first-order inexact primal-dual algorithm (I-PDA) for solving a class of convex-concave saddle point problems. The I-PDA, which involves a relative error criterion and generalizes the classical PDA, has the advantage of solving one subproblem inexactly when it does not have a closed-form solution. We show that the whole sequence generated by I-PDA converges to a saddle point solution with O (1 / N) ergodic convergence rate, where N is the iteration number. In addition, under a mild calmness condition, we establish the global Q-linear convergence rate of the distance between the iterates generated by I-PDA and the solution set, and the R-linear convergence speed of the nonergodic iterates. Furthermore, we demonstrate that many problems arising from practical applications satisfy this calmness condition. Finally, some numerical experiments are performed to show the superiority and linear convergence behaviors of I-PDA. [ABSTRACT FROM AUTHOR]

Crack is one of the common problems in preparation of NiCrBSi alloy coatings by laser cladding, especially for high hardness coatings. In this study, the crack behavior and prevention of Ni60A coating by coaxial laser cladding are investigated. The results indicate that the nonuniform hard Cr-rich precipitates and large residual tensile stress are the main reason for cracking of Ni60A coating. According to the difference of thermophysical properties and temperature between the coating and the substrate, the thermal stress models are established, in which the stress perpendicular to the scanning direction σ y is smaller than the stress along the scanning direction σ x . Due to the change in the relative relationship among σ x , σ y and fracture strength σ f , the crack distribution changes from network to parallel, until to no crack with the increasing line energy and the decreasing powder feed rate. And the angle θ 0 between the direction of resultant stress of σ x and σ y and Y-axis is 52.85°, which fits with the direction of long and short cracks in network crack distribution. In addition, the substrate preheating can effectively reduce cracking rate of Ni60A coating and completely prevent crack when preheated up to 500 °C. Also, the crack-free coating can be obtained by the combination of preheating to 300 °C and placing insulated plank under the substrate, which can reduce thermal damage of the substrate and obtain higher microhardness. [ABSTRACT FROM AUTHOR]

We design and analyze a C 0 interior penalty method for the approximation of classical solutions of the Dirichlet boundary value problem of the Monge–Ampère equation on convex polygonal domains. The method is based on an enhanced cubic Lagrange finite element that enables the enforcement of the convexity of the approximate solutions. Numerical results that corroborate the a priori and a posteriori error estimates are presented. It is also observed from numerical experiments that this method can capture certain weak solutions. [ABSTRACT FROM AUTHOR]

The weighted complementarity problem (denoted by WCP) significantly extends the general complementarity problem and can be used for modeling a larger class of problems from science and engineering. In this paper, by introducing a one-parametric class of smoothing functions which includes the weight vector, we propose a smoothing Newton algorithm with nonmonotone line search to solve WCP. We show that any accumulation point of the iterates generated by this algorithm, if exists, is a solution of the considered WCP. Moreover, when the solution set of WCP is nonempty, under assumptions weaker than the Jacobian nonsingularity assumption, we prove that the iteration sequence generated by our algorithm is bounded and converges to one solution of WCP with local superlinear or quadratic convergence rate. Promising numerical results are also reported. [ABSTRACT FROM AUTHOR]

This work identified new treatments to develop red raspberries for baking applications for better consumer appeal. Fresh or frozen fruits are often incorporated in baked products such as muffins and pies. These baked products are very popular due to their fresh, fruity flavor. Raspberries are used as an ingredient in many foods due to their delicious flavor. However, the incorporation of red frozen raspberries turns the baked product red due to syneresis during baking. In this study, we developed baking-stable red raspberries to minimize syneresis during baking. We applied three treatments to the red raspberries: vacuum impregnation with low methoxyl pectin and calcium chloride at 20 °C and a vacuum level of 50.8 kPa, for 7 min; partial dehydration using hot air at a dry bulb temperature of 65 °C until the final water content of 0.65 g H2O/g fruit was reached; and edible coatings at different concentrations. Treated berries were stored in a freezer at − 35 °C for 2 months. We determined the mechanical properties, drip loss, and visual integrity of the frozen-thawed red raspberries before baking to select appropriate coatings. Raspberry muffins were then baked to 204 °C for 20 min. We determined the syneresis from the baked fruit using an image analyzer. Findings indicate that sodium alginate coating on red raspberries at 0.4% (w/v) resulted in minimal syneresis in baked muffins at 13.9%, while commercially frozen raspberries showed syneresis at 62.9%. The maximum force (FM) and gradient (GC) values as firmness indicators were improved from control berries (7.45 N and 2.06 N/mm, respectively) to treated berries (21.16 N and 7.06 N/mm, respectively). [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid polysulfone (PSF)-titanium dioxide (TiO2) hollow fiber ultrafiltration (UF) membranes were prepared by sol–gel process and dry–wet spinning method. The effects of added TiO2 nanoparticles on membranes properties and morphologies were investigated by SEM, FT-IR, DSC, contact angle goniometer, UF experiments and so on. The results show that the membrane is a double-row finger-like pore structure, and with the increase of TiO2 content, the volume of finger-like pores increases first and then decreases. The organic–inorganic network structure forms between the TiO2 nanoparticles and the PSF chain introduced by the sol–gel method leads to an increase in the porosity, mechanical strength and thermal stability of the membrane. The addition of TiO2 improves the hydrophilicity, permeability and anti-fouling properties of the membrane. However, high TiO2 concentration induces nanoparticles aggregate, resulting in the decline of hydrophilicity, permeability and anti-fouling properties. So added the right amount of TiO2 nanoparticles can give the membrane better UF performance, mechanical properties and antifouling properties as well as longer service life. [ABSTRACT FROM AUTHOR]

Convergence rates are established for an inexact accelerated alternating direction method of multipliers (I-ADMM) for general separable convex optimization with a linear constraint. Both ergodic and non-ergodic iterates are analyzed. Relative to the iteration number k, the convergence rate is O (1 / k) in a convex setting and O (1 / k 2) in a strongly convex setting. When an error bound condition holds, the algorithm is 2-step linearly convergent. The I-ADMM is designed so that the accuracy of the inexact iteration preserves the global convergence rates of the exact iteration, leading to better numerical performance in the test problems. [ABSTRACT FROM AUTHOR]

Nonprecious metal catalysts are known of significance for electrochemical N2 reduction reaction (NRR) of which the mechanism has been illustrated by ongoing investigations of single atom catalysis. However, it remains challenging to fully understand the size-dependent synergistic effect of active sites inherited in substantial nanocatalysts. In this work, four types of small iron clusters Fen (n = 1–4) supported on nitrogen-doped graphene sheets are constructed to figure out the size dependence and synergistic effect of active sites for NRR catalytic activities. It is revealed that Fe3 and Fe4 clusters on N4G supports exhibit higher NRR activity than single-iron atom and iron dimer clusters, showing lowered limiting potential and restricted hydrogen evolution reaction (HER) which is a competitive reaction channel. In particular, the Fe4-N4G displays outstanding NRR performance for "side-on" adsorption of N2 with a small limiting potential (−0.45 V). Besides the specific structure and strong interface interaction within the Fe4-N4G itself, the high NRR activity is associated with the unique bonding/antibonding orbital interactions of N-N and N-Fe for the adsorptive N2 and NNH intermediates, as well as relatively large charge transfer between N2 and the cluster Fe4-N4G. [ABSTRACT FROM AUTHOR]

The rise of the engine remanufacturing industry has resulted in increased possibilities of energy conservation during the remanufacturing process, and scheduling could exert significant effects on the energy performance of manufacturing systems. However, only a few studies have specifically addressed energy-efficient scheduling for remanufacturing. Considering the uncertain processing time and routes and the operation characteristics of remanufacturing, we used the crankshaft as an illustrative case and built a fuzzy job-shop scheduling model to minimize the energy consumption during remanufacturing. An improved adaptive genetic algorithm was developed by using the hormone modulation mechanism to deal with the scheduling problem that simultaneously involves parallel machines, batch machines, and uncertain processing routes and time. The algorithm demonstrated superior performance in terms of optimal value, run time, and convergent generation in comparison with other algorithms. Computational results indicated that the optimal scheduling scheme is expected to generate 1.7 kW · h of energy saving for the investigated problem size. In addition, the scheme could improve the energy efficiency of the crankshaft remanufacturing process by approximately 5%. This study provides a basis for production managers to improve the sustainability of remanufacturing through energy-aware scheduling. [ABSTRACT FROM AUTHOR]

A series of Ca4La6(SiO4)4(PO4)2O2: Ce3+, Tb3+ phosphors have been investigated systematically, including the luminescence properties, energy transfer processes, and thermal stabilities. The phosphor exhibited a blue Ce3+ emission band and green Tb3+ emission peaks upon Ce3+ excitation in the UV region. Tunable emission color from blue to green could be obtained by adjusting the Tb3+ content. For the Ca4La6(SiO4)4(PO4)2O2: 0.06Ce3+, 1.20Tb3+ phosphor, the internal quantum yield reached 72% due to the efficient energy transfer and it presented good color stability when heated. The results suggest that the present phosphors show attractive performances for UV-pumped white-light-emitting diodes applications. [ABSTRACT FROM AUTHOR]

Ready-to-eat macaroni and cheese filled in novel oxygen scavenger and metal oxide–coated high-barrier polymer packages were processed in pilot scale 915-MHz microwave-assisted thermal sterilization system (MATS). Also, aluminum foil packages were processed in Allpax retort system to compare packaging performance. Physicochemical and sensory attributes of macaroni and cheese packaged in different oxygen and water vapor transmission rates were evaluated and stored for 6 months at 37.8 °C. Findings showed oxygen transmission rate (OTR) increase by 2–7 times and water vapor transmission rate (WVTR) increase by 2.5–24 times after MATS processing. OTR of polymeric packaging had no significant effect on vitamin A and vitamin E, shear force, and food color. Comparable results between polymeric and aluminum foil packaging were observed throughout the shelf life. This indicates that oxygen scavenger and high-barrier packaging with OTRs ~ 0.03–0.34 cc/m2 day and WVTRs ~ 0.62–7.19 g/m2 day can be used for ready-to-eat meals with extended shelf life for soldiers and astronauts. [ABSTRACT FROM AUTHOR]

The lipid droplet (LD)-associated protein adipose differentiation-related protein (ADRP or PLIN2) is required for the formation and stability of the LD organelle, whereas its biological roles are still obscure. Herein, we show that PLIN2 is the most abundant protein on the lipid droplets (LDs) of mouse myoblast cell line C2C12. Both the expression of PLIN2 and the accumulation of LDs were up-regulated in a time- and dose-dependent manner when the cells were treated with oleate (OA). The protein level of PLIN2 was positively correlated with the formation of LDs, suggesting that LDs stabilize PLIN2. Furthermore, knocking out PLIN2 in C2C12 cells led to enlarged LDs and higher triacylglycerol hydrolysis activity. The isolated PLIN2 null LDs became closely contact with mitochondria and other cellular organelles. Additionally, mitochondrial activity was suppressed by OA in PLIN2 null cells. Our results reveal the pivotal roles of PLIN2 in governing LD dynamics and their relationship to mitochondria, and suggest a reciprocal stabilization between PLIN2 and LDs. [ABSTRACT FROM AUTHOR]

Uniformly optimal convex programming algorithms have been designed to achieve the optimal complexity bounds for convex optimization problems regardless of the level of smoothness of the objective function. In this paper, we present a generic framework to extend such existing algorithms to solve more general nonlinear, possibly nonconvex, optimization problems. The basic idea is to incorporate a local search step (gradient descent or Quasi-Newton iteration) into the uniformly optimal convex programming methods, and then enforce a monotone decreasing property of the function values computed along the trajectory. While optimal methods for nonconvex programming are not generally known, algorithms of these types will achieve the best known complexity for nonconvex problems, and the optimal complexity for convex ones without requiring any problem parameters. As a consequence, we can have a unified treatment for a general class of nonlinear programming problems regardless of their convexity and smoothness level. In particular, we show that the accelerated gradient and level methods, both originally designed for solving convex optimization problems only, can be used for solving both convex and nonconvex problems uniformly. In a similar vein, we show that some well-studied techniques for nonlinear programming, e.g., Quasi-Newton iteration, can be embedded into optimal convex optimization algorithms to possibly further enhance their numerical performance. Our theoretical and algorithmic developments are complemented by some promising numerical results obtained for solving a few important nonconvex and nonlinear data analysis problems in the literature. [ABSTRACT FROM AUTHOR]

Inexact alternating direction multiplier methods (ADMMs) are developed for solving general separable convex optimization problems with a linear constraint and with an objective that is the sum of smooth and nonsmooth terms. The approach involves linearized subproblems, a back substitution step, and either gradient or accelerated gradient techniques. Global convergence is established. The methods are particularly useful when the ADMM subproblems do not have closed form solution or when the solution of the subproblems is expensive. Numerical experiments based on image reconstruction problems show the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

The molten pool temperature during laser engineered net shaping (LENS) could directly affect the microstructure and phase compositions of materials in the molten pool, thereby affecting the mechanical properties of the fabricated parts. To achieve a well-built solid structure, the research on fundamentals and methods of molten pool thermal behavior monitoring is of great significance. Using a high-resolution infrared camera, this paper realized real-time temperature tracking of Inconel 718 deposition in the LENS process. The effects of deposition variables, such as laser power and scanning speed, on the molten pool temperature and cooling rate have been investigated. In addition, the effects of the molten pool temperature on the molten pool depth and dendrite arm spacing (DAS) have been analyzed. The results suggest that the molten pool temperature increases with increasing of the laser power while it drops first and then rises with increasing of the scanning speed. The molten pool temperature increases nonlinearly with increasing of the number of layers during the material deposition process. [ABSTRACT FROM AUTHOR]

In this paper, we develop a parameterized proximal point algorithm (P-PPA) for solving a class of separable convex programming problems subject to linear and convex constraints. The proposed algorithm is provable to be globally convergent with a worst-case O(1 / t) convergence rate, where t denotes the iteration number. By properly choosing the algorithm parameters, numerical experiments on solving a sparse optimization problem arising from statistical learning show that our P-PPA could perform significantly better than other state-of-the-art methods, such as the alternating direction method of multipliers and the relaxed proximal point algorithm. [ABSTRACT FROM AUTHOR]

Enantioselectivity in environmental behavior and toxic effect of chiral pesticides has been received much attention. In this study, enantioselective bioactivity towards target organism Botrytis cinerea, acute toxicity and bioaccumulation in Eisenia fetida, and degradation in five kinds of soil under laboratory conditions regarding triazole fungicide tebuconazole were investigated. The results showed that fungicidal activity to Botrytis cinerea of R-(−)-tebuconazole was 44 times higher than S-(+)-tebuconazole with an order of R-(−)-tebuconazole > rac-tebuconazole > S-(+)-tebuconazole. No significant difference was found in acute toxicity of rac-, R-, and S-tebuconazole to E. fetida with 48-h EC50 of 10.78, 10.48, and 10.84 μg/cm2, respectively. Dissipation of tebuconazole in the five tested soils varied upon soil characteristics with half-life ranging from 32.2 to 216.6 days. Enantioselective and rapid dissipation of tebuconazole were observed in soils Hainan and Huajiachi, compared to the other soils. Enantioselective accumulation of tebuconazole in E. fetida was found with a preferential of S-(+)-tebuconazole although no significant difference in acute toxicity to E. fetida between rac-tebuconazole and enantiomers. The results indicated that S-(+)-tebuconazole with less fungicidal activity may be more likely to be accumulated in earthworm E. fetida. This research is helpful to better evaluate the environmental and ecological risk of tebuconazole on enantiomeric level. [ABSTRACT FROM AUTHOR]

The alternating direction method of multipliers (ADMM) has been proved to be effective for solving separable convex optimization subject to linear constraints. In this paper, we propose a generalized symmetric ADMM (GS-ADMM), which updates the Lagrange multiplier twice with suitable stepsizes, to solve the multi-block separable convex programming. This GS-ADMM partitions the data into two group variables so that one group consists of p block variables while the other has q block variables, where p≥1 and q≥1 are two integers. The two grouped variables are updated in a Gauss-Seidel scheme, while the variables within each group are updated in a Jacobi scheme, which would make it very attractive for a big data setting. By adding proper proximal terms to the subproblems, we specify the domain of the stepsizes to guarantee that GS-ADMM is globally convergent with a worst-case O(1/t) ergodic convergence rate. It turns out that our convergence domain of the stepsizes is significantly larger than other convergence domains in the literature. Hence, the GS-ADMM is more flexible and attractive on choosing and using larger stepsizes of the dual variable. Besides, two special cases of GS-ADMM, which allows using zero penalty terms, are also discussed and analyzed. Compared with several state-of-the-art methods, preliminary numerical experiments on solving a sparse matrix minimization problem in the statistical learning show that our proposed method is effective and promising. [ABSTRACT FROM AUTHOR]

Although InO nanofibers (NFs) are well-known candidates as active materials for next-generation, low-cost electronics, these NF based devices still suffer from high leakage current, insufficient on-off current ratios ( I / I ), and large, negative threshold voltages ( V ), leading to poor device performance, parasitic energy consumption, and rather complicated circuit design. Here, instead of the conventional surface modification of InO NFs, we present a one-step electrospinning process (i.e., without hot-press) to obtain controllable Mg-doped InO NF networks to achieve high-performance enhancement-mode thin-film transistors (TFTs). By simply adjusting the Mg doping concentration, the device performance can be manipulated precisely. For the optimal doping concentration of 2 mol%, the devices exhibit a small V (3.2 V), high saturation current (1.1 × 10 A), large on/off current ratio (>10), and respectable peak carrier mobility (2.04 cm/(V·s)), corresponding to one of the best device performances among all 1D metal-oxide NFs based devices reported so far. When high- κ HfO thin films are employed as the gate dielectric, their electron mobility and V can be further improved to 5.30 cm/(V·s) and 0.9 V, respectively, which demonstrates the promising prospect of these Mg-doped InO NF networks for highperformance, large-scale, and low-power electronics. [ABSTRACT FROM AUTHOR]

We study an inexact proximal stochastic gradient (IPSG) method for convex composite optimization, whose objective function is a summation of an average of a large number of smooth convex functions and a convex, but possibly nonsmooth, function. Variance reduction techniques are incorporated in the method to reduce the stochastic gradient variance. The main feature of this IPSG algorithm is to allow solving the proximal subproblems inexactly while still keeping the global convergence with desirable complexity bounds. Different subproblem stopping criteria are proposed. Global convergence and the component gradient complexity bounds are derived for the both cases when the objective function is strongly convex or just generally convex. Preliminary numerical experiment shows the overall efficiency of the IPSG algorithm. [ABSTRACT FROM AUTHOR]

Because of their unique physical and chemical properties, one-dimensional (1-D) metal-oxide nanostructures have been extensively applied in the areas of gas sensors, electrochromic devices, nanogenerators, and so on. Solar water-splitting has attracted extensive research interest because hydrogen generated from solar-driven water splitting is a clean, sustainable, and abundant energy source that not only solves the energy crisis, but also protects the environment. In this comprehensive review, the main synthesis methods, properties, and especially prominent applications in solar water splitting of 1-D metal-oxides, including titanium dioxide (TiO), zinc oxide (ZnO), tungsten trioxide (WO), iron oxide (FeO), and copper oxide (CuO) are fully discussed. [ABSTRACT FROM AUTHOR]

Hybrid inorganic-organic heterojunction solar cells (HHSCs) are successfully fabricated using SbS as a light-absorbing semiconductor, TiO nanorods (NRs) as an electron-transport layer, and poly-3 (hexylthiophene) (P3HT) as both a hole conductor and light absorber. The enhanced photo-to-electric conversion performance is expected to (1) enhance optical absorption in the visible light region by SbS and (2) photo-generate highly efficient charge carrier separation at TiO/SbS and SbS/P3HT heterojunction interfaces. The power conversion efficiency (PCE) of HHSCs improves approximately fourfold by inserting the SbS layer, which can be further enhanced about four more times by optimizing the length of TiO nanorod arrays (NRAs). Finally, the mechanism to illustrate the effect of the length of TiO NRs on the PCE is discussed. This leads to a theory for achieving high-efficiency inorganic-organic solar cells. [ABSTRACT FROM AUTHOR]

The soft failure of mechanical equipment makes its performance drop gradually, which occupies a large proportion and has certain regularity. The performance can be evaluated and predicted through early state monitoring and data analysis. In this paper, the support vector machine (SVM), a novel learning machine based on the VC dimension theory of statistical learning theory, is described and applied in machinery condition prediction. To improve the modeling capability, wavelet transform (WT) is introduced into the SVM model to reduce the influence of irregular characteristics and simultaneously simplify the complexity of the original signal. The paper models the vibration signal from the double row bearing and wavelet transformation and SVM model (WT-SVM model) is constructed and trained for bearing degradation process prediction. Besides Hazen plotting position relationships is applied to describe the degradation trend distribution and a 95 % confidence level based on $$t$$ -distribution is given. The single SVM model and neural network (NN) approach is also investigated as a comparison. The modeling results indicate that the WT-SVM model outperforms the NN and single SVM models, and is feasible and effective in machinery condition prediction. [ABSTRACT FROM AUTHOR]

Specimens of UNS S 31600 stainless steel with precast crack were treated under different discharge parameters. An elliptic hole formed ahead of the crack tip and the thermal compressive stress caused during electropulsing treatment cause the crack arresting. The factors affecting the curvature radius of the crack tip were studied. The crack arrest effect was examined by tensile test and fatigue test. Scanning electron microscopy (SEM), electro backscatter diffraction (EBSD), and transmission electron microscope (TEM) were employed to examine the changes of specimen before and after the treatment. The local recrystallization occurred around the crack tip. The experimental results indicate that the curvature radius of the crack tip is proportional to discharge parameter and crack length. The relationship between discharge parameter and the effectiveness of crack arrest can be obtained. [ABSTRACT FROM AUTHOR]

In this paper a new trust region method with simple model for solving large-scale unconstrained nonlinear optimization is proposed. By employing the generalized weak quasi-Newton equations, we derive several schemes to construct variants of scalar matrices as the Hessian approximation used in the trust region subproblem. Under some reasonable conditions, global convergence of the proposed algorithm is established in the trust region framework. The numerical experiments on solving the test problems with dimensions from 50 to 20,000 in the CUTEr library are reported to show efficiency of the algorithm. [ABSTRACT FROM AUTHOR]

Polymer-based packaging with low oxygen (OTR) and water vapor transmission rates (WVTR) can be used to limit oxidative chemical changes in packaged foods, especially for the 3- to 5-year shelf life required for military rations and long-duration space foods. Microwave-assisted thermal sterilization (MATS) produces higher quality food with a potentially longer shelf life as a result of volumetric heating and the associated shorter process time. This study investigated the effects of the package-MATS process interactions and the resultant package barrier properties on food quality, using a mashed potato model food following MATS process of F = 9 min for 12 weeks at 50 °C. Two poly ethylene terephthalate (PET)-based (MFA, MFC) and one ethylene vinyl alcohol (EVOH)-based (MFB) retort pouches were tested, with OTRs of 0.20, 2.11, and 0.07 cc/m·day and WVTRs of 2.64, 1.78, and 0.29 g/m·day for MFA, MFB, and MFC, respectively; a foil double-sealed MFA pouch served as a control (MF0). Barrier properties did not influence oxygen content in polymer pouches during storage ( p > 0.05). From the third week to the fifth week of storage, significant differences ( p < 0.05) were observed in total color difference (Δ E) and oxidation indicators (TBARS, hexanal, and nonanal). The mashed potato treated in higher barrier property pouches exhibited less color change and oxidation than those in lower barrier property pouches. The performance of the MFC pouch was similar overall to that of the metal pouch. These findings suggested that high-barrier packages are suitable for MATS or other commercially sterile foods, particularly for long shelf-life purpose. [ABSTRACT FROM AUTHOR]

This paper considers a class of constrained stochastic composite optimization problems whose objective function is given by the summation of a differentiable (possibly nonconvex) component, together with a certain non-differentiable (but convex) component. In order to solve these problems, we propose a randomized stochastic projected gradient (RSPG) algorithm, in which proper mini-batch of samples are taken at each iteration depending on the total budget of stochastic samples allowed. The RSPG algorithm also employs a general distance function to allow taking advantage of the geometry of the feasible region. Complexity of this algorithm is established in a unified setting, which shows nearly optimal complexity of the algorithm for convex stochastic programming. A post-optimization phase is also proposed to significantly reduce the variance of the solutions returned by the algorithm. In addition, based on the RSPG algorithm, a stochastic gradient free algorithm, which only uses the stochastic zeroth-order information, has been also discussed. Some preliminary numerical results are also provided. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to evaluate and quantify the energy consumption and environmental emissions of a refrigeration compressor produced by a Chinese factory throughout the entire compressor life cycle and try to determine the stage with the strongest environmental impact. The study covers all relevant life cycle stages, from raw material production to compressor use and final disposal. The research is conducted in accordance with ISO 14040/14044 standards. Methods: Life cycle assessment (LCA) methodology is applied in this study, and Chinese Life Cycle Database is used for the assessment. The evaluation results are presented in terms of individual impact category according to the characterization model (CML 2001) and normalization references (Laurent et al. 16:401-409, ). The following seven impact categories are considered: global warming potential, acidification potential, eutrophication potential, photochemical ozone formation potential, ozone depletion potential, ecotoxicity, and primary energy demand. All necessary energy and material flows are detailed for assessment purposes. Results and discussion: LCA results show that the compressor use stage in the life cycle consumes the most energy and exerts the strongest environmental impact, followed by the stages of raw material production and component manufacturing. Meanwhile, primary energy demand, ecotoxicity, and global warming potential are three predominant impact categories along with the entire life cycle of the refrigeration compressor; which account for 36.2150, 34.4567, and 16.5862 % of total impacts, respectively. Conclusions: Results show that the compressor use stage may be improved given that environmental impact is largely influenced by electricity requirement. Further investigation must be conducted to improve compressor service efficiency. [ABSTRACT FROM AUTHOR]

The propagation of laser-generated wedge waves in a wedge was investigated using digital shearing speckle interferometry based on a Michelson interferometer. Different from traditional measuring methods, the laser beam provides illumination on the surface of the wedge to generate wedge waves, and another laser beam was used as the probe beam. The beam that reflected from the surface passed through an interferometric setup, a Michelson interferometer that allowed imaging the out-of-plane surface displacements. From a series of interferograms taken by a charge coupled device, the propagation of wedge waves along the wedge tip could be visualized. [ABSTRACT FROM AUTHOR]

We propose a new gradient method for quadratic programming, named SDC, which alternates some steepest descent (SD) iterates with some gradient iterates that use a constant steplength computed through the Yuan formula. The SDC method exploits the asymptotic spectral behaviour of the Yuan steplength to foster a selective elimination of the components of the gradient along the eigenvectors of the Hessian matrix, i.e., to push the search in subspaces of smaller and smaller dimensions. The new method has global and $$R$$ -linear convergence. Furthermore, numerical experiments show that it tends to outperform the Dai-Yuan method, which is one of the fastest methods among the gradient ones. In particular, SDC appears superior as the Hessian condition number and the accuracy requirement increase. Finally, if the number of consecutive SD iterates is not too small, the SDC method shows a monotonic behaviour. [ABSTRACT FROM AUTHOR]

Three typical metal hypophosphite flame retardants La(HPO)·HO (LHP), Ce(HPO)·HO (CHP), and Al(HPO) (AHP) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis (TG), derivative thermogravimetric analysis, and differential thermal analysis. The thermal degradation products from the synthesized metal hypophosphites were also investigated using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and thermogravimetry coupled with mass spectrometry (TG-MS). The synthesized metal hypophosphites were also used as flame retardants for poly (1,4-butylene terephthalate) (PBT), and the combustion properties of flame-retarded PBT were evaluated using the limiting oxygen index and UL-94 tests. The results showed that the metal hypophosphites LHP, CHP, and AHP can be used as effective flame retardants for PBT, and these compounds can be obtained through a simple precipitation method. TG-FTIR and TG-MS results showed that the degradation process of AHP involves two steps, corresponding to the removal PH reaction and the further dehydration reaction of the hydrogen phosphate aluminum. While LHP and CHP have three degradation steps, the additional step is due to that LHP and CHP which will loss the crystal water at lower temperature. [ABSTRACT FROM AUTHOR]

Recently an affine scaling, interior point algorithm ASL was developed for box constrained optimization problems with a single linear constraint (Gonzalez-Lima et al., SIAM J. Optim. 21:361-390, ). This note extends the algorithm to handle more general polyhedral constraints. With a line search, the resulting algorithm ASP maintains the global and R-linear convergence properties of ASL. In addition, it is shown that the unit step version of the algorithm (without line search) is locally R-linearly convergent at a nondegenerate local minimizer where the second-order sufficient optimality conditions hold. For a quadratic objective function, a sublinear convergence property is obtained without assuming either nondegeneracy or the second-order sufficient optimality conditions. [ABSTRACT FROM AUTHOR]

The remanufacturing blanks with cracks were considered as irreparable. With utilization of detour effect and Joule heating of pulsed current, a technique to arrest the crack in martensitic stainless steel FV520B is developed. According to finite element theory, the finite element(FE) model of the cracked rectangular specimen is established firstly. Then, based on electro-thermo-structure coupled theory, the distributions of current density, temperature field, and stress field are calculated for the instant of energizing. Furthermore, the simulation results are verified by some corresponding experiments performed on high pulsed current discharge device of type HCPD-I. Morphology and microstructure around the crack tip before and after electro pulsing treatment are observed by optical microscope(OM) and scanning electron microscope(SEM), and then the diameters of fusion zone and heat affected zone(HAZ) are measured in order to contrast with numerical calculation results. Element distribution, nano-indentation hardness and residual stress in the vicinity of the crack tip are surveyed by energy dispersive spectrometer(EDS), scanning probe microscopy(SPM) and X-ray stress gauge, respectively. The results show that the obvious partition and refined grain around the crack tip can be observed due to the violent temperature change. The contents of carbon and oxygen in fusion zone and HAZ are higher than those in matrix, and however the hardness around the crack tip decreases. Large residual compressive stress is induced in the vicinity of the crack tip and it has the same order of magnitude for measured results and numerical calculation results that is 100 MPa. The relational curves between discharge energies and diameters of the fusion zone and HAZ are obtained by experiments. The difference of diameter of fusion zone between measured and calculated results is less than 18.3%. Numerical calculation is very useful to define the experimental parameters. An effective method to prevent further extension of the crack is presented and can provide a reference for the compressor rotor blade remanufacturing. [ABSTRACT FROM AUTHOR]

Purpose: Life cycle assessment (LCA) is a useful tool for quantifying the overall environmental impacts of a product, process, or service. The scientific scope and boundary definition are important to ensure the accuracy of LCA results. Defining the boundary in LCA is difficult and there are no commonly accepted scientific methods yet. The objective of this research is to present a comprehensive discussion of system boundaries in LCA and to develop an appropriate boundary delimitation method. Methods: A product system is partitioned into the primary system and interrelated subsystems. The hierarchical relationship of flow and process is clarified by introducing flow- and process-related interventions. A system boundary curve model of the LCA is developed and the threshold rules for judging whether the system boundary satisfies the research requirement are proposed. Quantitative criteria from environmental, technical, geographical and temporal dimensions are presented to limit the boundaries of LCA. An algorithm is developed to identify an appropriate boundary by searching the process tree and evaluating the environmental impact contribution of each process while it is added into the studied system. Results and discussion: The difference between a limited system and a theoretically complete system is presented. A case study is conducted on a color TV set to demonstrate and validate the method of boundary identification. The results showed that the overall environmental impact indicator exhibits a slow growth after a certain number of processes considered, and the gradient of the fitting curve trends to zero gradually. According to the threshold rules, a relatively accurate system boundary could be obtained. Conclusions: It is found from this research that the system boundary curve describes the growth of life cycle impact assessment (LCIA) results as processes are added. The two threshold rules and identification methods presented can be used to identify system boundary of LCA. The case study demonstrated that the methodology presented in this paper is an effective tool for the boundary identification. [ABSTRACT FROM AUTHOR]