We address the question: \Are some classes of combinatorial optimization problems intrinsically harder than others, without regard to the algorithm one uses, or can diiculty only be assessed relative to particular algorithms?" We provide a measure of the hardness of a particular optimization problem for a particular optimization algorithm and present two algorithm-independent quantities that us...

friction-stir welding process is a novel method of solid state welding, which produces heat due to friction between the pin, the shoulder and the workpiece. this heat causes a paste area. shoulder pressure and pin spin cause edges integration and lead to welding. in this study, firstly, the feasibility of welding of steel sheet (en10130) with a thickness of 1.5mm has been tested by 58 experimen...

It becomes a great challenge in the research area of metaheuristics to predict the hardness of combinatorial optimization problem instances for a given algorithm. In this study, we focus on the hardness of the traveling salesman problem (TSP) for 2-opt. In the existing literature, two approaches are available to measure the hardness of TSP instances for 2-opt based on the single objective: the ...

We study the impact of backbones in optimization and approximation problems. We show that some optimization problems like graph coloring resemble decision problems, with problem hardness positively correlated with backbone size. For other optimization problems like blocks world planning and traveling salesperson problems, problem hardness is weakly and negatively correlated with backbone size, ...

Measurement of the strength of brittle materials, such as resin composites, is extremely difficult. Micro-indentation hardness testing is a convenient way of investigating the mechanical properties of a small volume of material. In this study, the mechanical properties of five commercially available flowable resin composites were investigated by the dynamic micro-indentation method. Additionall...

chewable ferrous fumarate tablet is the best iron dosage form for children due to better compliance and lower teeth staining compared to the oral drop. because of the different desirable properties of chewable tablets and the opposing effects of fillers on them, the mathematical experimental design was used as the formulation approach. different series of formulations based on single filler (la...

The continuous optimization of processing technology and evaluation methods is an important way to achieve high quality efficiency for difficult-to-process materials. To solve the problem frequent defects in slot, ultrasonic vibration-assisted slot-milling (UVASM) was developed titanium alloy. Simultaneously, comparative experiments were carried out between UVASM conventional slot milling (CSM)...