Strength Analysis of the MSBS-5.56B Rifle Handguard Assembly Loaded with an Under-Barrel Grenade Launcher

This paper presents the results of FEM (finite element method) numerical testing of the handguard of the MSBS-5.56B 5.56 mm calibre rifle complete with a 40 mm calibre under-barrel grenade launcher. The FEM calculations and the analysis of the calculations were intended to provide verification of the strength of the handguard subjected to the forces generated by the interaction with the grenade launcher during the launch of a grenade round. The results of the tests allowed the designers and process engineers to design the optimal shape of a handguard that will guarantee its safety during the operation of the rifle with the under-barrel grenade launcher.

An Integrated Group Decision-Making Approach Considering Uncertainty Conditions

The management of business information processes needs effective decision-making models. That means to involve different methods, techniques, and principles to improve competitiveness and to achieve the planned business results. In this context, the article deals with the problem of group decision-making under uncertain conditions. To cope with such problems some well-known optimization strategies of Wald, Laplace, Hurwitz, and Savage are modified to take into account the experts’ opinions with different importance when forming the final group decision. Numerical testing is based on a case study for CRM software selection. The results are discussed based on the proposed models under two different cases derived from the case study. The conducted numerical testing of the proposed models demonstrates their applicability to cope simultaneously with multiple experts’ evaluations and uncertainty conditions.

A Framework for Extension of Dynamic Finite Element Formulation to Flexural Vibration Analysis of Thin Plates

Dynamic Finite Element formulation is a powerful technique that combines the accuracy of the exact analysis with wide applicability of the finite element method. The infinite dimensionality of the exact solution space of plate equation has been a major challenge for development of such elements for the dynamic analysis of flexible two-dimensional structures. In this research, a framework for such extension based on subset solutions is proposed. An example element is then developed and implemented in MAT LAB software for numerical testing, verification, and validation purposes. Although the presented formulation is not exact, the element exhibits good convergence characteristics and can be further enriched using the proposed framework.

A Framework for Extension of Dynamic Finite Element Formulation to Flexural Vibration Analysis of Thin Plates

Dynamic Finite Element formulation is a powerful technique that combines the accuracy of the exact analysis with wide applicability of the finite element method. The infinite dimensionality of the exact solution space of plate equation has been a major challenge for development of such elements for the dynamic analysis of flexible two-dimensional structures. In this research, a framework for such extension based on subset solutions is proposed. An example element is then developed and implemented in MAT LAB software for numerical testing, verification, and validation purposes. Although the presented formulation is not exact, the element exhibits good convergence characteristics and can be further enriched using the proposed framework.

Finite volume approach for fragmentation equation and its mathematical analysis

This work is focused on developing a finite volume scheme for approximating a fragmentation equation. The mathematical analysis is discussed in detail by examining thoroughly the consistency and convergence of the numerical scheme. The idea of the proposed scheme is based on conserving the total mass and preserving the total number of particles in the system. The proposed scheme is free from the trait that the particles are concentrated at the representative of the cells. The verification of the scheme is done against the analytical solutions for several combinations of standard fragmentation kernel and selection functions. The numerical testing shows that the proposed scheme is highly accurate in predicting the number distribution function and various moments. The scheme has the tendency to capture the higher order moments even though no measure has been taken for their accuracy. It is also shown that the scheme is second-order convergent on both uniform and nonuniform grids. Experimental order of convergence is used to validate the theoretical observations of convergence.

Distributed and Asynchronous Coordination of a Mixed-Integer Linear System via Surrogate Lagrangian Relaxation

With the emergence of Internet of Things that allows communications and local computations, and with the vision of Industry 4.0, a foreseeable transition is from centralized system planning and operation toward decentralization with interacting components and subsystems, e.g., self-optimizing factories. In this paper, a new “price-based” decomposition and coordination methodology is developed to efficiently coordinate subsystems such as machines and parts, which are described by Mixed-Integer Linear Programming (MILP) formulations, in a distributed and asynchronous way. To ensure low communication requirements, exchanges between the “coordinator” and subsystems are limited to “prices” (Lagrangian multipliers) broadcast by the coordinator, and to subsystem solutions sent to the coordinator. Asynchronous coordination, however, may lead to convergence difficulties since the order in which subsystem solutions arrive at the coordinator is not predefined as a result of uncertainties in communication and solving times. Under realistic assumptions of finite communication and solve times, convergence of our method is proved by innovatively extending Lyapunov Stability Theory. Numerical testing of generalized assignment problems through simulation demonstrates that the method converges fast and provides near-optimal results, paving the way for self-optimizing factories in the future.

Design of a marine propeller for scale racing boats in a speed and energy efficiency contest

The process of optimized design, evaluation and manufacturing of high energy efficiency propellers for competition boats at scale is addressed in this research. This project uses the stages of hydrodynamic design, numerical testing and manufacturing of four prototypes as example. During the hydrodynamic design, three design methodologies were compared, namely: Blade Element Theory, lifting line theory and design based on DTMB propeller series. The objective function of the optimized design is based on obtaining the chord and pitch distribution that generates the greatest thrust, speed and efficiency. Similarly, the performance of each prototype was evaluated by CFD in a virtual channel registering thrust, torque and speed. Finally, the additive manufacturing process applied is presented. Prototyped propellers present efficiencies and maximum speeds approximately 15% higher than recommended commercial propellers for this type of boats. This study was developed by the Hydrometra group in the framework of the international competition Hydrocontest 2017.

Design of magnetoelectric machines with annular armature winding

Design strategy of synchronous machines with annular armature winding and rotor placed PMs is discussing, which can provide advantages instead of general ones with drum armature winding in two-pole machine magnetic systems with developed outer diameter. Tie derivations between of stator bore volume, torque and electromagnetic loads via Magnetic constant (Arnold’s), equations for linear load, for PMs magnetic conductivity in dependence from rated parameters of magnetically hard material, for phase’s EMF. Slots filling by areas of rectangular wires and of coil and major insulation are taking into consideration. Numerical testing, executed via torque-angle (static) curves calculation by means of finite-element method, shows that the motors, that designed with appropriated torque multiplicity are satisfying to initial technical requirements, that is confirms methodic validity. During numerical testing tooth harmonics, provided by stator tooth structure, influence was evaluating and was given recommendations for reduction this influence. The results of power and torque characteristics comparison with traditional machine supplied by drum winding represented, which confirms capability of declared advantages receipt.

Computing Nearest Correlation Matrix via Low-Rank ODE’s Based Technique

For n-dimensional real-valued matrix A, the computation of nearest correlation matrix; that is, a symmetric, positive semi-definite, unit diagonal and off-diagonal entries between −1 and 1 is a problem that arises in the finance industry where the correlations exist between the stocks. The proposed methodology presented in this article computes the admissible perturbation matrix and a perturbation level to shift the negative spectrum of perturbed matrix to become non-negative or strictly positive. The solution to optimization problems constructs a gradient system of ordinary differential equations that turn over the desired perturbation matrix. Numerical testing provides enough evidence for the shifting of the negative spectrum and the computation of nearest correlation matrix.