The construction site and its elements create circumstances that are conducive to the formation of safety risks during the execution of works. Analysis indicates the critical importance of these factors in the set of characteristics that constitute the causes of accidents in the construction industry. The main substantive tasks in this article include isolating patterns of accidents on the site and identifying the analysed characteristics that are important in defining these patterns. In terms of methodology, the paper presents affinity analysis as the method of analysing data resources. The research was carried out on the basis of data from the register kept by the District Labour Inspectorate in Krakow (2014–2016).

High-performance, self-compacting concrete (HPSCC) represents a very significant step in the development of concrete technology. The most important features of SCC are specific rheological properties which include flowability, segregation resistance and passing ability. Therefore, a crucial requirement is to maintain an appropriate balance between the slump flow and plastic viscosity of concrete mixtures. In general, the rheological properties are modified by effective superplasticisers and a proper ratio of water to binder. The aim of this study is to focus on the important aspect of the impact of shape of the coarse aggregate on fresh concrete mixture properties and the strength of high-performance, self-compacting concrete (HPSCC).

This paper focuses on the estimation of life cycle cost of buildings taking into account the influence of risk.
The authors present a original model for the estimation of the life cycle cost of a building object which allows quantifying the degree of cost increase arising from the incurred and assessed risks. The operation of the model is demonstrated by a relevant example.

The railway investment in Poland is subject to many random factors, which have a significant impact on extending the deadline and increasing the planned cost. Railway investments are characterized by their distinctiveness in comparison to other construction works. To minimize the occurrence of unforeseen, random risks in future rail investments, the authors attempted to identify and indicate the most likely of them. The analysis concerns the implementation of railway investments in Poland, taking into account its legal and technical characteristics. The basic method of identifying the hazards of railway investments in Poland was a case study. The main threats were: bad preparation of the main contractor, difficulties in obtaining maps for design purposes, delay in the design documentation with external stakeholders, the award of contractor closures, difficulties in carrying out works related to encountering undeclared underground infrastructure and other hidden obstacles as well as the influence of the contracting party's internal procedures on the course of the contract.

Maintaining the financial liquidity of construction companies during the implementation of large investment contracts is one of the main budgetary problems when planning their schedules. Despitethe unquestioned, greater than ever, development of effective methods of planning, coordinating and controlling, the increase in the complexity of the organization's operating conditions makes it no easier to succeed in project management. This article attempts to analyse the impact of unplanned time and cost deviations on the liquidity of a construction project. Deviations from the planned costs and expenses incurred by the contractor were used as an example in this study.

In this article, the author analyses the state of the research of the multi-mode, resource-constrained, projectscheduling problem (MRCPSP). Both general and construction-industry-specific applications were studied and compared– in particular, algorithms and methodologies used for solving the different variations of this scheduling problem. Based on the analysis, the author suggests future research ideas.

The paper focuses on the meta-model notions and introduces new terminology to the meta-modeling
discipline. This terminology refers to the new concept of Context-Driven Meta-Modeling (CDMM), which
is more general then other approaches to defining modeling languages. In the result it extends the metamodeling domain vocabulary. All notions in the paper were introduced on the basis of the decomposition of responsibilities identified in meta-models. Till now modeling languages were assumed to be compact and monolithic structures, in contrast to good design practices, not being a subject of any decomposition. The system of notions introduced in the paper is general enough to be sufficient when Context-Driven Meta-Modeling Paradigm (CDMM-P) is combined with the traditional class-object paradigm.

This paper examines the effect of Archaea on wastewater treatment in sequencing biological reactors (SBR). The research was carried out in two SBR reactors: a reactor with activated sludge bioaugmented with Archaea (microorganisms which constitute a third domain besides Bacteria and Eukaryotes); a reactor with conventional activated sludge was used as a control. Archaea were incubated in laboratory conditions as recommended by Archaea Solutions Inc. The research revealed that the time period required for the acclimation of the activated sludge in the presence of Archaea was twice as long as in the case of regular nitrifying activated sludge. The observed nitrogen and phosphorous removal from wastewater was achieved to a higher extent in sludge with Archaea and the sludge itself settled faster. The required concentration of oxygen in the reactor with Archaea was lower than in the classic set-up – this resulted in lowering the operating costs of the treatment plant. Furthermore, the denitrification process was significantly shorter and did not require nitrate nitrogen (V).

We define bf(n) to be the smallest integer (a natural number) d such that numbers f(n1 , n2 , ..., nm), where n1+n2+ ... + nm ≤ n are not divisible by d. For the given functions f : ℕm → ℕ, we will obtain the asymptotic characterisation of the sequence of the least non canceled numbers (bf (n))n∈ℕ. In the case f : ℕ2 (k, l)→k3+l3∈ℕ, this characterisation can be rewritten in the terms of the permutations polynomials of finite commutative quotient ring ℤ/mℤ. There are situations in which we cannot expect formula for bf(n) to be simple, but we can provide the upper and lower bounds of it.

The thesis presents the analysis of the pneumatic tube system, one of the solutions in material handling. Contemporary solution components of pneumatic tube systems were presented and described, such as: blowers, diverters, send/receive stations, carriers, air brakes and system couplers. For the purpose of the article, a bypass air brake was built at the Laboratory of Techno-Climatic Research and Heavy Duty Machines of the Cracow University of Technology. , which was then tested. The aim of the test was to determine the minor loss coefficient ζ, depending on the degree of the air brake valve override. The measurement results are given in the work.

Our developed cell model of the mass transfer for the computation and prediction output parameters in a roll dewatering process of fibre materials by distributed pressure are presented. The model makes it possible to determine relationships between residual moisture content of fibre material and input parameters of the dewatering process.

Critical impeller rotational speeds for having a solid suspension in a liquid and for gas dispersion in the slim vessel with two independently driven impellers were determined. An A-315 impeller functioned as the lower impeller whereas a Rushton turbine was fixed higher with gas being fed right below the latter. We investigated what influence on this rotational speed was had by the distance between the impellers, their rotational direction, solid concentration, solid particle size and gas flow rate. Results obtained for the twoand three-phase systems were compared. In the three-phase systems, we also measured the power input in order to assess the efficiency of mixing.

The study evaluated the impact of emissions (VOCs) as a result of the operation of the printing of plant at
working positions of those performing their tasks outdoors or in buildings next door to the subject of the printing installation (offset printing). The first part of the paper presents the general characteristics of the process and materials used for printing. The further part shows the results of the modelling of emissions,
depending on the operating state of purification (emission in normal conditions and emission conditions, which deviate from normal – failure state of the afterburner).

The paper presents the results of experimental studies of the enhancement of the boiling process of a zeotropic agent with high temperature glide inside tubes at a low heat flux density. It discusses the effect of three types of inserts on the heat transfer process and the flow resistances during boiling of R407C in vertical tubes. The experimental studies covered measurements of heat transfer coefficient values, flow resistance values and thermal efficiency in the measurement section.

An investigation of sorption kinetics of heavy metal ions on polysaccharide materials has been performed. Traditionally, kinetic study of ion exchange sorption begins with a determination of the slowest stage of the proces, but the stage of chemical reaction between heavy metal ions and the sorbent functional groups can also make essential contribution. Results of kinetic studies were treated using different kinetic models and, experimental data are described most adequately with pseudo-second order kinetic model. It is determined that polysaccharide materials used in the studies have relatively good kinetic characteristics.

This paper presents several ways of calculating real and theoretical energy efficiency coefficients of vapour compression heat pumps in short and long time. Differences in the calculation are associated with taking into account, among others, various components of the heat pump responsible for the consumption of electricity, steady state or transient conditions, part or the nominal load ratio of heat pump. The calculation results are compared with the values of coefficients, which have been obtained theoretically.

In areas with scattered buildings and a low population density, the sewage management infrastructure is underdeveloped. Until recently, the only practical solution was to make a non-effluent and tight tank: a septic tank, which was one of the means to carry sewage away from detached houses in areas without sewage systems. Currently, domestic sewage treatment plants are highly popular. The paper shows the operating principle of a septic tank and a domestic treatment plant and analyses their advantages and disadvantages. Particular attention was paid to the economical aspect.

A method of calculating the apparatus of combined action for carrying out a high-temperature reaction in a fluidised bed of the solid reactant particles is proposed based on a system approach. In this bed, the
reaction proceeds simultaneously with the continuous grinding of the formed products and the processes of heat and mass transfer are significantly intensified in connection with the constant renewal (denudation) of the reaction surface both due to the impact fracture of the product shell in the zones of the intensive collision in the counterflows of the reacting particles and its abrasion in the body of the fluidised bed.

An optimal way to select parameters of a driver’s seat of a special vehicle, which contributes directly to an increase in driving comfort is presented in the work. A mathematical model of the vehicle was formulated by using of joint coordinates and homogenous transformations. A maneuver of driving over obstacles in a form of a speed bump of different heights and lengths is presented. A subject of the investigations was to select such damping parameters and driver’s seat stiffness to minimize amplitudes of vibrations present in this subassembly. An influence of a form of an objective function and a selection of decisive variables on quality of the optimization results obtained was analyzed.