Novel Perspectives of Engineering Research Vol. 1

The article aims to analyze the influence of the number of passes on the tube in a shell and tubes condenser heat exchanger using the concepts of efficiency and effectiveness and examines the effect of the number of passes in a shell and tubes condenser heat exchanger, with an inlet pressure of R134a refrigerant in the shell equal to 1.2 Mpa. Water or a water-based nanofluid with a percentage of aluminum oxide nanoparticles passes through the tubes (Al₂O₃). The heat exchanger is divided into three sections by the methods used: overheated, saturated, and subcooled. Efficiency and effectiveness were the primary metrics utilized to assess the heat exchanger's thermal performance. In the superheated steam area, efficiency is close to 1.0. However, there is scope for improvement in terms of thermal efficiency, which can be improved with more significant tube passes. The saturated steam region procedure is efficient for lower mass flow rates of the fluid in the tube, but it is ineffective for higher mass flow rates of the fluid in the tube. It is, nonetheless, quite effective at large mass flow rates. In the subcooled area, there is plenty of room to improve efficiency. Even so, more heat exchange in the subcooled area is limited by the fluid inlet temperature in the pipe and the work refrigerant pressure.

Last several years, the author has been involved in studies of phonons and their structure-properties correlation on several advanced functional materials that included not only flexible framework materials, Te-based oxides, and perovskites but also recently established low dimensional 2D materials, namely graphene, TiS₃ nanosheet and nanofiber, VSe₂ nanosheet, SnO₂ nanoparticles. In this book chapter, the phonons and mode Grüneisen parameters of a flexible framework compound H₃[Co(CN)₆] is presented in an elaborate manner. H₃[Co(CN)₆] belongs to a class of flexible framework structured cyanides that exhibit negative thermal expansion  along c-axis. In-situ high-pressure Raman spectroscopic studies on H₃[Co(CN)₆] in a diamond-anvil cell were carried out under hydrostatic pressure from ambient to 11 GPa. From the evolution of Raman spectra, splitting of bands and discontinuous changes in the pressure dependence of band frequencies, a phase transition from trigonal-monoclinic is identified at 2.3 GPa. In contrast to other bands, a lattice band at 140 cm^-1 and the Co-CN deformation band at 348 cm^-1 were soften with increase in pressure. Mode Grüneisen parameters (y_i) were obtained for the ambient trigonal phase using the pressure dependencies of Raman mode frequencies (d\(\Omega\)/dP). Absence of Raman band with flat spectral feature was found as the compound amorphized around 11 GPa.

The development of new methods of physicochemical analysis opens vast opportunities for studying the kinetics and mechanisms of the structure formation in cement systems. A study of the structure formation and cement hardening processes will allow widening a range of methods of their control and developing production techniques for advanced composite materials. The objective of the work is to study the mechanism of structure formation processes using digital technologies. The X-ray microtomography system is used to analyze the formation of alternating dark and bright concentric rings both on the surface and in the bulk of the specimens. It is supposed that the formation of concentric rings is caused by the generation of acoustic vibrations in the cement-water system at early stages of the structure formation.

A method for preventing piping, or for reducing the exit hydraulic pressure gradient or ground-water seepage is the use of cutoff walls and drainage holes. In gravity dams, cutoff walls are usually made from concrete with a vertical geometry under the dam foundation. Inclination of cutoff walls may be chosen by engineers if it shows a positive effect on the reduction of uplift force. The objective of this study is to investigate the effectiveness of inclined cutoff walls under hydraulic structures, considering the influence of depth, location, and inclination angles of the cutoff wall using the finite element method (FEM). This study compares the efficiency of inclined cutoff walls located under a gravity dam. The cutoffs have angles ranging from 0 to 60 degrees with respect to the vertical direction and are angled in downstream direction. Different positions of cutoff walls with various angles of inclination are used. Results show that minimum uplift force occurs when the cutoff wall is at the heel (upstream) of the dam. With fixed longitudinal cutoff wall placement, inclined walls reduce the uplift force. The effect of an inclined cutoff wall upstream of the dam for reducing uplift force is very high. Although the numerical simulation showed that the inclined cutoff wall was able to reduce the uplift force, it is important to note that the construction of an inclined cutoff wall will be more difficult than the construction of a vertical cutoff wall. Therefore, in future studies, the investigation of inclined cutoff wall construction and their utilization need further analysis. Estimating the project construction costs is an important consideration.

Composite soil stabilization involves addition of two or more modifiers such as river sand and inorganic chemical such as cement to lateritic soil. This measure has a dual effect on the behavior of the soil structure. River sand provides volume stability while the inorganic chemical accelerates chemical bonding and ensures reduction of permeability. The soil structure increases in strength, durability as well as a reduction in deformability.  To improve the engineering qualities of natural soil, composite soil stabilization relies on treating it to both physical and chemical treatments. Ideally stabilization of weak soil has a basic objective. It is to find the most efficient and economical method so that the properties of a relatively weak soil are improved to withstand any imposed or shearing stresses.  The main objective here is to examine the changes and particulate system distribution of coastal lateritic soil and stress response to imposed mechanical systems as well as contact behavior on application of various stabilizers. The most common purpose of soil treatment is to improve shear strength and loading capacity, as well as stability and settlement control.

Calcium is the most important component for soil stabilization in all instances. In addition to plasticity reduction, Portland cement, by its inherent nature of producing strength – developing hydration products, provides improved strength and durability. As a result, the effectiveness of stabilization is based on the number of positions of exchangeable ions – mineralogical composition which is related to liquid limit and the amount of liberated calcium ions from cement [% of cement, % of compaction and curing time] which influences the durability [bonding effect] and unconfined compressive strength [bearing capacity]. The lateritic soil formation within the area under investigation is predominantly dilatant in nature. In order to deploy this material for construction purpose adequate [composite] treatment is required. Additionally, stone base as a feature of design by practitioners has assumed alarming proportion. This has increased the cost of construction to a very high pedestal.  This research is designed to investigate the origin of this dilatant laterization and to verify viable but economic means of treatment [stabilization] to reduce to barest minimum the escalating cost of modifying this material for deployment in engineering and construction operations. It is very crucial as it will provide an in-depth knowledge of some engineering properties of lateritic soils within the coastal plains of Akwa Ibom State.

The article examines all the existing and lost mosaics displayed on public and residential buildings in the territory of Volgograd and Volzhsky. The issues of typology and stylistics of mosaics are also examined. The classification of the features of mosaic compositions has been carried out. The author makes an attempt to summarize and scientifically comprehend the creative work of Volgograd monumental artists. The article is supported by archival and exterior photographs. Many city mosaics are lost or significantly damaged. Therefore, it is important to study and preserve monumental art and carry out urgent restoration work where necessary.

When designing pressure vessels, it is quite important to know the loads exerted on the nozzle by the connecting pipework. However the piping reactions computed by the piping structural analysis are often not available at the vessel design stage. To overcome this problem, the pressure vessel must be exclusively designed for the internal design pressure, after which the permissible external loads for the nozzle- vessel intersection as well as for the nozzle-piping connection (flange) can be calculated. In this way the load limits and load capacity of the nozzle can be determined and are available at an early stage to the piping designer (pipe stress analyst). Successively it is the responsibility of the piping designer to ensure that the piping reactions are kept within the permissible load limits of the pressure vessel nozzle. The advantage of this approach is that the imposed loads does not necessitate thickening of the pressure retaining shell of the vessel nor require additional reinforcing pads around the nozzle neck. Moreover it should be noted that by increasing the vessel shell thickness or adding a reinforcing pad, the nozzle becomes more rigid and therefore a better approximation to a fixed point or anchor thus effectively eliminating the advantage of any nozzle flexibility. This approach avoids remedial work of pressure vessels and/or pipework at late stages of a project, which for sure has negative impact on project costs and schedule. In summary, the objective of this study is to ensure that the pipe stress analyst has access to individually allowable nozzle loads at an early stage of the project. The developed algorithm described in Table 1 thru 4 can be used for this task. By applying the load interaction rule, the pipe stress analyst can evaluate the piping reactions computed with the aid of formal pipe stress analysis software.

The main characteristic of any complex oscillatory process, which is the oscillatory process of soils during strong earthquakes, is the spectrum of periods of the oscillatory process. The values of the periods of vibration of soils and ground buildings and structures during strong earthquakes play a major role in studying the behavior of ground structures and ensuring its safety. Seismic impact refers to dynamic impacts in which the greatest impact is due to resonance phenomena, i.e. coincidence or closeness of the periods of ground vibration and free vibrations of a ground structure. The content of this chapter is devoted to a comprehensive study of methods for the theoretical and experimental determination of the exact, simplified and approximate values of the prevailing periods from simple homogeneous to complex multi-layer subsoil. The values of the periods of numerous examples of real subsoil are given. Comparative estimates of the values of the periods (including the periods of the highest modes of vibration) are given, calculated theoretically from microseismic vibrations of soils and from accelerograms of the soil during a real earthquake. The work is of the opinion that during earthquakes the soils vibrate with similar values with such periods. Having the values of the periods of soil vibrations, it is possible to reasonably choose which buildings and structures are advisable to build from the point of view of ensuring their seismic resistance on such soils. This is the most important task of seismic microzoning and earthquake-resistant construction. As an integral characteristic of complex soil conditions for establishing their categories according to seismic properties, it is proposed to take the values of the main prevailing period, since it is shown in the work that its formation is influenced by all physical, mechanical and geometric characteristics of all layers. An analysis of the data of normative documents of different countries on earthquake-resistant construction on the values of the coefficients of soil conditions and spectra of reactions, depending on the categories of soils (periods), as well as their distance from active faults and the magnitude of the earthquake is given. In conclusion, the text emphasizes that the process of seismic impact in the first approximation occurs as follows:seismic waves propagating from the seismic focus generate ground motions on Earth’s surface with predominant periods equal to the periods of free oscillations of the near-surface thickness, which in turn, cause new vibrations with predominant periods equal to the free oscillation periods of the structures. This means during an earthquake seismic waves are “filtered” twice: first in the near-surface stratum, and then in the structure itself.