Since G.E.P. Box introduced central composite designs in early fifties of 20th century, the classic design of experiments (DoE) utilizes response surface models (RSM), however usually limited to the simple form of low-degree polynomials. In the case of small size datasets, the conformity with the normal distribution has very weak reliability and it leads to very uncertain assessment of a parameter statistical significance. The bootstrap approach appears to be better solution than - theoretically proved but only asymptotically equal - t distribution based evaluation. The authors presents the comparison of the RSM model evaluated by a classic method and bootstrap approach.
The subject of outsourcing of personnel services are functions and auxiliary tasks in the operation of a given enterprise. It is based on outsourcing specific tasks and entire personnel processes, as well as hiring employees who carry out tasks entrusted by a client. The main problem faced by enterprises is employee turnover caused by numerous absences, sick leave and holidays, and, as a consequence, employees have more and more delays and do not keep their deadlines. Consequently, they are frustrated that they have to perform more duties from other positions and listen to complaints about continuous decline in work efficiency. The problem of employee turnover is becoming a common phenomenon. Therefore, each company should analyse this problem. Starting from identifying the problem and, as a result, implementing appropriate measures to prevent excessive fluctuation of employees. It is also important to enable employees to develop and organize appropriate working conditions, which will ensure the comfort of work and attachment to the employer.
The article presents the results of the use of SPC tools, i.e. control charts and indicators of the qualitative capability to assess the stability and capability of the production process of rolled products - I-sections. Statistical analysis of the collected data regarding the selected feature of the analysed product - the width of the foot, and the normality of the distribution were done, which showed that the obtained distribution of measurement results is not a normal distribution. As a result, appropriate SPC procedures for non-normal distribution were used. The Pareto-Lorenzo diagram and FMEA method were also used to obtain information about the structure of non-conformities of the analysed product and the level of risk associated with them. This information was used to propose corrective actions and improve the production process of rolled products.
The Small and Medium Enterprises (SMEs) are the backbone of all the major economies around the world. Majority of these industries are facing tough environment for existence. The present study explored the most common and easily implementable Lean Tools/Techniques amongst the SMEs. This has been achieved via a detailed survey of SMEs in India. Study concludes with nine most common Lean Tools/Techniques implemented across the surveyed population of Indian SMEs.
Remotely piloted operations of lightweight Unmanned Air Vehicles (UAV) are limited by transmitter power consumption and are always restricted to Line-of-Sight (LOS) distance. The use of mobile cellular network data transfer services (e.g. 3G HSPA and LTE) as well as long-range terrestrial links (e.g. LoraWAN) makes it possible to significantly extend the operation range of the remotely piloted UAV. This paper describes the development of a long-range communication solution for the UAV telemetry system. The proposed solution is based on (but not restricted to) cellular data transfer service and is implemented on Raspberry Pi under Gentoo Linux control. The goal of the project is to develop a flexible system for implementing optimized redundant network solutions for the Non-LOS remote control of the UAV
The concept of lean management in an organization, improving products and processes using the Lean Manufacturing concept, is discussed in this paper. Striving for excellence is the key factor in maintaining competitiveness on the market. Only organizations able to adapt to changing environmental conditions faster than others achieve an advantage, and the management in line with the Lean Manufacturing philosophy is de facto change management. In this paper, important factors in the ceramic industry, which should be taken into account when implementing Lean Manufacturing are characterized. Important factors affecting the implementation of lean tools include, such as: the size of the enterprise, involvement of employees, knowledge about the Lean concept, technological factor, type and variety of the product line, as well as the specificity of the ceramic industry. The greatest opportunity associated with the implementation of Lean is to increase the competitiveness of the company obtained through: meeting the quality and economic expectations of customers. The greatest opportunity associated with implementation of the Lean is to increase competitiveness of the company obtained through: meeting the quality and economic expectations of their customers. Practice shows, however, that despite the simplicity of rules and tools, few organizations manage to achieve the level of excellence of the pioneer of this concept, the Japanese Toyota Corporation.
In the future there will be a lot of changes and development concerning autonomous transport that will affect all participants of transport. There are still difficulties in organizing transport, but with the introduction of autonomous vehicles more challenges can be expected. Recognizing and tracking horizontal and vertical signs can cause a difficulties for drivers and, later, for autonomous systems. Environmental conditions, deformity and quality affect the perception of signals. The correct recognition results in safe travelling for everyone on the roads. Traffic signs are designed for people that is why the recognition process is harder for the machines. However, nowadays some developers try to create a traffic sign that autonomous vehicles can use. Computer identification needs further development, as it is necessary to consider cases where traffic signs are deformed or not properly placed. In the following investigation, the advantages and disadvantages of the different perception methods and their possibilities were gathered. A methodology for the classification of horizontal and vertical traffic signs anomalies that may help in designing better testing and validation environments for traffic sign recognition systems in the future was also proposed.
Understanding the effect of powder feedstock alterations during multicycle additive manufacturing on the quality of built components is crucial to meet the requirements on critical parts for aerospace engine applications. In this study, powder recycling of Alloy 718 during electron beam melting was studied to understand its influence on fracture behavior of Charpy impact test bars. High resolution scanning electron microscopy was employed for fracture surface analysis on test bars produced from virgin and recycled powder. For all investigated samples, an intergranular type of fracture, initiated by non-metallic phases and bonding defects, was typically observed in the regions close to or within the contour zone. The fracture mode in the bulk of the samples was mainly moderately ductile dimple fracture. The results show a clear correlation between powder degradation during multi-cycle powder reuse and the amount of damage relevant defects observed on the fracture surfaces. In particular, samples produced from recycled powder show a significant amount of aluminum-rich oxide defects, originating from aluminum-rich oxide particulates on the surface of the recycled powder.
L. Medvecky, R. Stulajterova, M. Giretova, J. Mincik, M. Vojtko, J. Balko and E. Petrovova
The aim was to investigate the enamel health benefits of a novel toothpaste with active tetracalcium phosphate/monetite mixtures under de/remineralization cycling. The enamel de/remineralization cycling protocol was consisted of demineralization in 1% aqueous solution of citric acid at pH 3.6 with following treatment with toothpastes and soaking in remineralization storage solution. Effectiveness of toothpastes to promote remineralization was evaluated by surface microhardness measurements, enamel erosion depth, analysis of surface roughness and fluorescent optical method. The novel tetracalcium phosphate/monetite toothpaste had the same remineralization potential as commercial calcium silicate/phosphate toothpaste and significantly higher than control storage solution group (p<0.05). Surface roughness was significantly lower after addition of fluorides to dentifrice (p<0.05). The enamel erosion depth was significantly reduced by applying toothpastes as compared to negative control (p<0.05) and did not differ from calcium silicate/phosphate toothpaste (p>0.66). The results showed that dentifrice formulations containing active tetracalcium phosphate/monetite mixture with or without fluoride addition had excellent enamel remineralization potential under de/remineralization cycling and successfully promote remineralization of enamel with daily using in the form of toothpaste.
Due to its durability, tungsten carbide has long been used as a material to produce dental burs. WC– Co burs are designed for smooth, efficient cutting and extended life. Dental burs are available in different sizes and shapes, for example round burs, pear and cylinder-shaped, egg-shaped, as well as there are various tapered ones, which enable an individual selection of the drill for the right treatment. Carbides can be used for standard crowns and bridges, for extensive surgical procedures and they should minimize damage to the existing teeth. The design of WC–Co dental bur reduces a patient’s discomfort because of the operating time and the fact that its liquidity is preserved. The head of the bur (the cutting edge) delivers optimum concentricity and strength. The shank is made from stainless steel allowing a bur to be autoclaved multiple times without the risk of corrosion. The main purpose of this study was to evaluate the wear of a tungsten carbide dental bur. The results of stereoscopy microscope and SEM/EDS analysis are presented.