During the exploitation of buildings, cracks appear in the concrete of structural elements, which can reduce the physical and mechanical characteristics of their structures. With a certain exposure width and depth, cracks are subject to filling with special materials. In case of error in determining the crack depth, the repair material may not fill it sufficiently. This might lead to accidents. Nowadays, the most common method is to measure the parameters of cracks with a microscope and a measuring probe. Its disadvantage underlies in insufficient reliability of the crack depth measurement. This is because if there is an internal lintel of concrete residues in the crack, there may be an error in measuring its depth. The ultrasonic pulse method is also used, when the depth of the crack is determined by the time of travel of ultrasonic vibrations on the section of high-quality concrete and on the section with a crack. This method is not very reliable because the ultrasonic vibrations can also propagate through the internal lintel of the concrete residues in the crack. In this case, the measurement result will be false. An improved ultrasonic pulse method is used when the combined amplitude of the information signal is also measured. The use of this parameter is insufficient because solving the problem requires taking into account spectral characteristics of the parameter. At the stage of development, there is a method that uses surface ultrasonic waves. Its disadvantages are relative complexity of research in concrete and high cost of equipment. To increase the reliability and accuracy of determining the geometric parameters of cracks in concrete, studies were carried out using a complex ultrasonic pulse method. During the research, the value of the normalized propagation time of ultrasonic vibrations, the amplitude, and duration of the first half-period of the information signal were measured. The results of the research allow us to recommend the developed method for solving the problem.

The relevance of the introduction of HCL systems in production conditions, in which the dynamics of changes in the characteristics of light flux can be synchronized with the circadian biorhythms of the human body. This is determined by the fact that the unsatisfactory characteristics of industrial lighting increase the risk of injury and occupational morbidity. It is shown that providing only normative quantitative characteristics of illumination is not enough, since its qualitative characteristics – ripple coefficient, spectral composition cause non-visual effect of light. They can affect the psychophysiological state of a person, his\her performance, fatigue by affecting the circadian biorhythms of the body. The comparison of standard values of the level of artificial lighting of jobs in different countries with natural ones. Based on the analysis, recommendations were developed aimed at improving artificial lighting. The analysis of the results of the study of non-visual effect of the pulsation of the light flux on the psychophysiology of a person was carried out. Its main negative consequences are given, the necessary tasks for the implementation of the HCL program in a production environment in this aspect are identified. The results of analysis of studies of the influence of the color temperature of the light flux on the psychophysiological state of a person are also presented. Recommendations on the regulation of this parameter for various types of production activities have been developed.   Keywords: industrial lighting; NIF-effect; occupational injuries.

The use of concrete adhesive joints in repair and restoration works is an effective technological solution from technical and economical point of view. To make such joints, polymer glues are used, for example, epoxy, siloxane, acrylic, etc. The use of such technology reduces material consumption, labour costs, and time of construction works. The analysis of published research results showed that the use of acrylic adhesives is effective. When performing an adhesive concrete joint, the main task is to ensure the required strength of the adhesive structure during its operation. The analysis of publications revealed that the strength of the structure is influenced by the following main factors: external load, strength of concrete to be glued, gluing area, and the thickness of the glue layer. Currently, the influence of the specified factors is being studied on samples of adhesive structures using mechanical, press equipment. During the experiments, external loads are applied to the manufactured sample of the adhesive structure, for example, tensile, bending or shear forces. The measured parameter is the strength of the adhesive structure. With such studies, it is difficult to determine the value of the maximum external load that leads to the formation of microcracks, which makes the strength of the structure reduce. As a result, this approach can cause an error in research conclusions, which will lead to a decrease in the reliability of operation of a real construction object. In addition, this approach makes it impossible to control the condition of those adhesive concrete structures that are used on real construction sites. The developed methods to study adhesive concrete structures using the ultrasonic pulse method are based on the dependence of the speed of propagation and attenuation coefficient of ultrasonic vibrations on the relative change in the structure of the material under consideration. The application of the developed methods and instrumentation for their implementation allows determining the value of the maximum permissible external load and ensuring the control of the state of adhesive structures in terms of crack formation on real construction sites.

The extension of service life of operating building constructions requires a study of the current state of materials in their structural elements. The statement of the problem determines that such studies should be carried out using non-destructive methods, among which the ultrasonic pulsed method is one of the most effective ones. Its effectiveness lies in the efficiency of obtaining measurement data and their sufficient accuracy, as well as in comparative complexity of the measurement process. As a rule, the measurement of the required parameters of the ultrasonic signal is carried out in the presence of vibration interference generated by equipment, vehicles. Such obstacles are elastic waves that propagate in the material of the building object under consideration. As a result, vibration interference is imposed on the information ultrasonic signal. This leads to false measurement results, which can cause an error in estimating the current state of physical and mechanical properties of the material under consideration. Ultrasonic measuring instruments produced in Ukraine and abroad do not have protection from such vibration interference. To solve this problem, technical solutions have been recently developed based on the use of reference values of the controlled parameter of the ultrasonic signal; amplification of the information signal directly in the place of its fixation; and on the analysis of an array of information signals with the use of special software products for their statistical processing. However, the use of such technical solutions does not allow solving the problem completely. In order to solve the problem completely, the following solution was developed. The ideology of the measurement process includes the emission of ultrasonic probing signals and the reception of information signals at two fixed frequencies.