Comparison of problem solving tools in lean organizations

As global market competition is getting fiercer, and companies are looking at ways to stay on top, more and more organizations are looking at Lean Manufacturing and lean tools to support them in achieving their goals. Especially within the automotive industry, lean practices are very well received. The speed at which the automotive industry is evolving, especially but not only, in countries like Romania, leads to the need to carefully analyze lean manufacturing concepts, examine them against local production conditions, and to develop and standardize them. One of the most important things to take into consideration here is the application of an adequate problem solving technique to avoid waste. The objective of this research paper lies in analyzing and comparing the problem-solving methods recommended by the Toyota Production System, and to propose their appropriate application at shop floor, in relation to the specific problem type

Numerical-Experimental Study Regarding the Single Point Incremental Forming Process

The present paper proposes a numerical-experimental comparative study on the single point incremental forming process. A DC04 steel sheet with a thickness of 0.6 mm was used for both the numerical simulation using the finite element method and the experimental research. The type of trajectory used was a spiral trajectory and the finished part obtained was a truncated cone-shaped part. The analysis program used for simulation was Ls-Dyna. The simulations were performed in several variants: with a fixed mesh and with an adaptive mesh, using two different element formulations: 25 (Belytschko-Tsay formulation with thickness stretch) and -16 (fully integrated shell element modified for higher accuracy) and two contact types: automatic surface to surface (ASTS) and forming one way surface to surface (FOSS). The results of the numerical analysis and of the experimental research were focused on determining the major strain, minor strain, thickness reduction and forces at the end of the single point incremental forming process, as well as determining the processing time

Comparison of problem solving tools in lean organizations

As global market competition is getting fiercer, and companies are looking at ways to stay on top, more and more organizations are looking at Lean Manufacturing and lean tools to support them in achieving their goals. Especially within the automotive industry, lean practices are very well received. The speed at which the automotive industry is evolving, especially but not only, in countries like Romania, leads to the need to carefully analyze lean manufacturing concepts, examine them against local production conditions, and to develop and standardize them. One of the most important things to take into consideration here is the application of an adequate problem solving technique to avoid waste. The objective of this research paper lies in analyzing and comparing the problem-solving methods recommended by the Toyota Production System, and to propose their appropriate application at shop floor, in relation to the specific problem type

CARS: Context Aware Rate Selection for Vehicular Networks

Abstract—Traffic querying, road sensing and mobile content delivery are emerging application domains for vehicular networks whose performance depends on the throughput these networks can sustain. Rate adaptation is one of the key mechanisms at the link layer that determine this performance. Rate adaptation in vehicular networks faces the following key challenges: (1) due to the rapid variations of the link quality caused by fading and mobility at vehicular speeds, the transmission rate must adapt fast in order to be effective, (2) during infrequent and bursty transmission, the rate adaptation scheme must be able to estimate the link quality with few or no packets transmitted in the estimation window, (3) the rate adaptation scheme must distinguish losses due to environment from those due to hiddenstation induced collision. Our extensive outdoor experiments show that the existing rate adaptation schemes for 802.11 wireless networks underutilize the link capacity in vehicular environments. In this paper, we design, implement and evaluate CARS, a novel Context-Aware Rate Selection algorithm that makes use of context information (e.g. vehicle speed and distance from neighbor) to systematically address the above challenges, while maximizing the link throughput. Our experimental evaluation in real outdoor vehicular environments with different mobility scenarios shows that CARS adapts to changing link conditions at high vehicular speeds faster than existing rate-adaptation algorithms. Our scheme achieves significantly higher throughput, up to 79%, in all the tested scenarios, and is robust to packet loss due to collisions, improving the throughput by up to 256% in the presence of hidden stations. I

Minimizing the Main Strains and Thickness Reduction in the Single Point Incremental Forming Process of Polyamide and High-Density Polyethylene Sheets

Polymeric materials are increasingly used in the automotive industry, aeronautics, medical device industry, etc. due to their advantage of providing good mechanical strength at low weight. The incremental forming process for polymeric materials is gaining increasing importance because of the advantages it offers: relatively complex parts can be produced at minimum cost without the need for complex and expensive dies. Knowing the main strains and especially the thickness reduction is particularly important as it directly contributes to the mechanical strength of the processed parts, including in operation. For the design of experiments, the Taguchi method was chosen, with an L18 orthogonal array obtained by varying the material on two levels (polyamide and polyethylene) and the other three parameters on three levels: punch diameter (6 mm, 8 mm and 10 mm), wall angle (50°, 55° and 60°) and step down (0.5 mm, 0.75 mm and 1 mm). The output parameters were strain in the x direction, strain in the y direction, major strain, minor strain, shear angle and thickness reduction. Two analyses were conducted: signal-to-noise ratio analysis with the smaller-is-better condition and analysis of variance. The optimum values for which the thickness was reduced were the following: wall angle of 50°, punch diameter of 10 mm and step down of 0.75 mm

Database for restoration of cultural heritage objects

At present, it is very important to create on line databases for heritage objects (their characteristics and incurred treatments). Information provided by this database complete the analytical documentation of the objects to be restored. Our research group has elaborated such a database lasting for clear evidence of the performed interventions and the actual state of conservation, to ensure the possibility of exchange of information between researchers in the field, and to provide a friendly interface for limited time access and security of data. This paper presents results consistent with objectives

Structural Parameters and Behavior in Simulated Body Fluid of High Entropy Alloy Thin Films

The structure, composition and corrosion properties of thin films synthesized using the Pulsed Laser Deposition (PLD) technique starting from a three high entropy alloy (HEA) AlCoCrFeNix produced by vacuum arc remelting (VAR) method were investigated. The depositions were performed at room temperature on Si and mirror-like polished Ti substrates either under residual vacuum (low 10−7 mbar, films denoted HEA2, HEA6, and HEA10, which were grown from targets with Ni concentration molar ratio, x, equal to 0.4, 1.2, and 2.0, respectively) or under N2 (10−4 mbar, films denoted HEN2, HEN6, and HEN10 for the same Ni concentration molar ratios). The deposited films’ structures, investigated using Grazing Incidence X-ray Diffraction, showed the presence of face-centered cubic and body-centered cubic phases, while their surface morphology, investigated using scanning electron microscopy, exhibited a smooth surface with micrometer size droplets. The mass density and thickness were obtained from simulations of acquired X-ray reflectivity curves. The films’ elemental composition, estimated using the energy dispersion X-ray spectroscopy, was quite close to that of the targets used. X-ray Photoelectron Spectroscopy investigation showed that films deposited under a N2 atmosphere contained several percentages of N atoms in metallic nitride compounds. The electrochemical behavior of films under simulated body fluid (SBF) conditions was investigated by Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy measurements. The measured OCP values increased over time, implying that a passive layer was formed on the surface of the films. It was observed that all films started to passivate in SBF solution, with the HEN6 film exhibiting the highest increase. The highest repassivation potential was exhibited by the same film, implying that it had the highest stability range of all analyzed films. Impedance measurements indicated high corrosion resistance values for HEA2, HEA6, and HEN6 samples. Much lower resistances were found for HEN10 and HEN2. Overall, HEN6 films exhibited the best corrosion behavior among the investigated films. It was noticed that for 24 h of immersion in SBF solution, this film was also a physical barrier to the corrosion process, not only a chemical one

Exploring Clinical and Biological Features of Premature Births among Pregnant Women with SARS-CoV-2 Infection during the Pregnancy Period

Studies observed that women infected with SARS-CoV-2 during pregnancy had a higher risk of preterm birth. Although it is likely that COVID-19 during the late trimester of pregnancy can trigger premature birth, prematurity remains a concern, and it is vital to study additional clinical and biological patient factors that are highly associated with this negative pregnancy outcome and allow for better management based on the existing predictors. In order to achieve this goal, the current study retrospectively recruited 428 pregnant patients that were separated into three study groups using a 1:2:4 matching ratio and a nearest-neighbor matching method. Sixty-one pregnant patients had a history of COVID-19 during pregnancy and gave birth prematurely; 124 pregnant patient controls had COVID-19 and gave birth full-term, while the second control group of 243 pregnant patients had a premature birth but no history of COVID-19. It was observed that a symptomatic SARS-CoV-2 infection during the third trimester was significantly more likely to be associated with premature birth. Even though the rate of ICU admission was higher in these cases, the mortality rate did not change significantly in the COVID-19 groups. However, SARS-CoV-2 infection alone did not show statistical significance in determining a premature birth (β = 1.09, CI = 0.94–1.15, p-value = 0.067). Maternal anemia was the strongest predictor for prematurity in association with SARS-CoV-2 infection (β = 3.65, CI = 1.46–5.39, p-value < 0.001), followed by elevated CRP (β = 2.11, CI = 1.20–3.06, p-value < 0.001), and respectively IL-6 (β = 1.92, CI = 1.20–2.47, p-value = 0.001. SARS-CoV-2 infection is associated with an increased risk of preterm birth, as shown by our data. If SARS-CoV-2 infection arises during the third trimester, it is recommended that these patients be hospitalized for surveillance of clinical evolution and biological parameters, such as anemia and high inflammatory markers, which have a multiplicative influence on the pregnancy result