Advanced Aspects of Engineering Research Vol. 6

This paper presents the effects of the several factors that influence lateral-torsional buckling on freestanding circular arches. Studied factors that attribute to the effects of lateral-torsional buckling include cross section type, included angle, slender ratio, imperfection, loading, and boundary conditions. From the reviewed studies, the misrepresentation of these factors to a certain extent may yield inaccurate results. Several studies and design codes have proposed different solutions to account for these factors in designs against lateral-torsional buckling for some structural elements. However, there were no studies reported on the out-of-plane lateral-torsional buckling of fixed circular arches made of structural aluminum channel sections subjected to central concentrated load. There is a need for further research on the lateral-torsional buckling real behavior of fixed circular arches of structural aluminum channels.

In some massive constructions, like off-shore platforms, it is sometimes difficult or impossible to register the loading process during many years of exploitation. Knowing the input random processes characteristics, it sometimes seems promising to estimate the output characteristics using the structural dynamic equation. Following this approach, the spectral densities are employed into longevity estimation. Many methods for estimation of the fatigue damage thought the spectral densities are being still developed. The question here arises: is it reasonable to use the spectral approach in case of post-processing stage of the machines when the prototype exists and the loading process realization could be possibly recorded?  It is worth mentioning, that the ultimate goal of many authors of those methods is to achieve the results, similar to those, which are easily obtained directly from the RAINFLOW method. In the paper, the real loading process is analyzed. The aim of this paper is to show some contradictions of the spectral approach. In this paper, the short review with an analysis of the accuracy of the spectral method is presented. To show the fact, that some of the assumptions of spectral methods are doubtful, the method of the digitally modelled process is introduced. Most of all, the author wants to get the answer from the spectral methods adepts, why do they propose such a controversial way of estimation.

The field of education is filled with wide range of opportunities for the student community and it is a powerful device that decides their destiny. The students of today are very ambitious and in particular the engineering students are much determined to achieve in various domains. The acquisition of the practical knowledge of the engineering concepts and strong theoretical backgrounds is very essential, but the students finds many hurdles in acquiring the degree because of the academic constraints and one such is the fear towards the mathematical courses in their programme which deals with the science of reasoning, logical thinking and comprehension of the conceptualization of engineering principles and phenomena. This fear diminishes the subject interest and paralyse the performance and further affinity towards the courses.  This emotional aspect disintegrates the channel of learning mathematics. To refurbish the minds of the students a profound investigation has to been undertaken for which this paper is a step towards it. The method of multi-step FCM (Fuzzy Cognitive Maps) approach is applied in this paper to uncover the measures of mitigating the fear of mathematics among the engineering students from the teaching perspective. This method has more practical application as it helps in decision making in all fields. The results obtained will certainly facilitate the educators and academicians to device suitable strategies of mitigating the mathematical phobia in the students and streamline the optimistic waves to make them dive in positive initiatives.

Businesses that produce many complex products inevitably have disparate test requirements. Over time test solutions diverge despite having similarities contributing to increases in test cost. Mergers and acquisitions further complicate having common, well-understood, low-cost test platforms. By comparing the population of parameters tested across all products insight can be gained as to what groupings of parameters could have shared, common test platforms. The method described in this paper, in use today, describes a data mining and statistical approach to identify groups of test capability by testing ranges and limits, leveraging decades of historical testing data across a wide range of commercial products to design common test equipment at a large aerospace manufacturing organization. Clustering methods were used and evaluated to determine common factory test platform requirements, and compare them against existing test platform vendor capabilities. In conclusion, the construction of a database of historical testing data has become a foundational tool to develop a design for a common test platform.

Nowadays, the needs and requirements to avoid infections during surgical operations, require to be more imaginative than ever. The one-use textiles substrates that are used in hospitals can be, also, a way to transport the antibacterial effect around the own building. This is the main objective of this work; to use clothes and textiles surfaces as antibacterial systems using natural components. Microencapsulation has shown in several occasions the effectivity to protect and vehiculize active principles that can be used for medical treatments. In this case, essential oils have been used as antimicrobial agent, that when combined with shell polymers based on Chitosan of different molecular weight distribution and Arabic gum, allows them to act against Gram (+) and Gram (?) bacteria. Chitosan has been shown to be a biopolymer with a wide range of applications and is highly dependent on its molecular weight. The study of the efficiency of the final systems obtained present high valuable possibilities, due to its character similar to hydrogels. The influence of the molecular weight of biopolymers used, in a layer by layer approach (LbL), has been demonstrated and shows a very promising way to state a clear control on the delivery mechanisms. The essential oil used has a very volatile character formed by more than 40 components and with the help of FT-IR and TGA it has been possible to corroborate that all its components were encapsulated. The impregnation of the different samples to the tissue was successful and allowed the antibacterial study to be carried out, which was carried out in duplicate on each sample and demonstrated that they have bacterial activity.

One of the great advantages of electrospun fibers is the large tridimensional area produced, capable of storing any type of material. The aim of our investigation is to study the electrospinning technique to produce polymer membranes for drug delivery applications, given their large surface area and ability to transport a bioactive compound. A mathematical modeling of the delivery system kinetics was also studied to find the mechanism that controls the releasing process. Results showed that electrospinning could provide regular and smooth membranes suitable for drug delivery processes. The choice of a proper solvent for this process was an important parameter analyzed, because it determined whether fibers were capable of forming, as well as influencing fiber porosity. The mathematical modeling also proved that thicker PLLA membranes exhibited a Fickian diffusion behavior during the drug transport, presenting better control in drug delivery processes.

Visualization of factory production flow facilitates test optimization decision-making, given the complexity inherent in many organization’s manufacturing environments. Constructing production flow visualizations can be difficult and time-consuming, and has often involved expensive simulation software. In this paper we describe successful work populating NIST CMSD Core Manufacturing Simulation Data from existing factory data, visualizing factory flows using the open source D3.js visualization toolset. By mapping existing factory test data using the CMSD standard, the open source visualization toolset represents a lower-cost mechanism for understanding and optimizing test operations, detailed in this paper. The visualization was developed with a small team and deployed into production at a large aerospace manufacturer over the course of four months and is now used by multiple business units for factory flow optimizations of their complex engineered products.

Borate glasses containing Li₂O and fixed concentration of heavy metal oxide Bi₂O₃ are prepared by melt quenching technique. The effect of addition of Li₂O on borobismuthate glasses has been studied. Density of the glasses has been found to increase slightly with Li2O content whereas molar volume and glass transition temperature decreases. IR spectroscopy was used for structural studies of these glasses in the range from 400 to 4000 cm^-1. IR analysis showed that Bi³⁺cations are incorporated in the glass structure as (BiO₆) octahedral units and boron ions are incorporated as (BO₃) and (BO₄) units. As the L_i2O content increases in the glass, some of the BO₃ trigonal units get converted into BO₄ tetrahedral units and non-bridging oxygens have been formed^. The optical transmittance spectra have been recorded at room temperature. The cut-off wavelength shows a red shift, the optical band gap decreases and polarizability increases with Li₂O content. The compositional dependence of different physical properties such as density, molar volume optical band gap and optical basicity has been studied and correlated with the glass structure.

This research discusses the testing and analysis of cracking Aluminum (Al) material. Al as a handle lever was used for a braking device on a motor vehicle. Cracking of handle lever due to the part content of porosity from hydrogen gas. The existence of the H2 can be caused by the casting process and dies design that is less perfect, especially at the gate or brisket and overflow. This research is to optimize the process of making Al part handle lever, and the construction dies by following the standard. The results of these improvements were re-evaluated through the chemical and mechanical testing properties stages, such as density test and tensile test on the workpiece as part handle lever. The loads on the tensile test are 25 kg and 35 kg, and the tensile test result has met the standard set by the motor vehicle company. The optimization result has the porosity defect can be reduced by 99%. Therefore the best part handle lever can be produced. From the results clearly, show the improvements in the process have been successfully made, and the mechanical properties and safety have met the standards.

Bio-diesel is a sustainable, renewable and alternate fuel for CI Engines. The use of bio-diesel produces various durability issues on key components of CI engines. Its contribution towards global warming is lesser than that of diesel. For durability studies, the aspects considered are injector coking, carbon deposition on piston, lubricity of engine oil, wear and tear of piston and cylinder walls and corrosion of engine parts they come in contact with fuel. In this work, reports about the durability aspects, published by highly rated journals in scientific indexes, have been cited. From these reports, the effect of bio-diesel on engine durability are surveyed and analysed. The use of bio-diesel leads to injector coking, increased carbon deposition on piston, decreased viscosity of the lubricating oil and fuel dilution, increased engine wear and corrosion.

In the present work, an attempt is made to investigate wear behaviour of Al-7075 alloys made of Mica and Kaolinite. Specimens are prepared using stir casting technique in a temperature range of 800 to 850°C. Influence of Mica and Kaolinite reinforcements on the wear characteristic of the composite is analysed using experiments. Wear behaviour under constant load of 40 N is investigated using pin-on-disc test at room temperature, under dry condition. Experiments are conducted for different proportions of reinforcements used (2%, 4%, 6% and 8%). Results were found to predict an increase in wear behaviour with increase in weight percentage of reinforcements. The presence of mica and kaolinite in the matrix decreased wear loss by increasing wear resistance.

Researchers, system operators, engineers, and utility owners are working hard to fully utilise power system installed facilities in response to rising energy demand, which is posing security challenges for power systems. As a result, this paper uses risk-based security assessment to address the problem of power system security. A linearized risk-based method which uses fast decoupled load flow algorithm was used to assess the low voltage security of power systems. The method is based on the concept of risk, which considers both the likelihood of occurrence and the severity of the contingency. Risk is decomposable and can be decomposed by perverting the conditions that make the network risky. It requires the probability of voltage distribution, the probability of contingency and severity function to evaluate the impact of the contingency. The proposed method was illustrated on a real power system, the simulation model of the Nigerian 41 bus 330kV transmission grid network for calculating the risk indices of three simulated contingencies at various rates of occurrence. The calculated risk indices show that as the rate of occurrence increases, risk indices increase.  This means that contingencies with a high incidence rate but little effect have a higher or equal chance than contingencies with a large impact but occur infrequently. As a result, system operators, technicians, and engineers must quickly identify, investigate, and propose solutions to mitigate their effects on the network and improve service delivery.

The existing time-consuming menu-driven IVRs have been replaced by new blends of Speech Powered Interactive Voice Response (SEIVR) Systems. When transmitted via telecom networks that use narrowband codecs, however, the quality and intelligibility of the speech signal suffers significantly. Providing wideband quality signal without much modification of the existing network infrastructure can only be possible with a novel technique of Artificial Band Width Extension (ABWE). ABWE is implemented in this paper using a QMF filter bank that band splits the input speech into LF and HF components before compressing and encoding the HF components using a novel data hiding technique. A QMF synthesis filter bank is used in the reconstruction process to create an artificial wideband speech signal. For implementation of the proposed model, a client-server approach with socket programming on a single machine has been used assuming no noise and no transmission errors. A comparative analysis has also been done to find out the root cause for degradation in performances of SEIVR systems. The proposed SEIVR model with ABWE has shown a major improvement in speech recognition accuracy and overall efficiency in simulations. Based on the simulation findings, it can be concluded that the recognition accuracy of an artificially extended NB speech signal is superior to that of an NB speech signal and comparable to that of a WB speech signal.

Conducting polymer (CP) polypyrrole (PPy) and their nanocomposites (NCs) with metal oxide \(\alpha\)-Fe₂O₃ (CP/MO) are synthesized by in situ chemical oxidation polymerization using various oxidants and dopants by keeping different molar percentage of MO with monomers. The prepared CPs and their CP/MO NCs PPy/\(\alpha\)-Fe₂O₃ are characterized by FTIR. Their morphology has studied by SEM and TEM techniques. Presence of identity bonds on the FTIR spectrograms ensures the formation of CPs and their NCs. SEM images show the presence of nearly spherical nanoparticles (NPs) on surface of CP and its composites. TEM images show the presence of NPs embed polymer net having thickness below 20 nm in PPy and, nanocluster/nanorods/nanosheets embed polymer chain of spherical NPs in composites, PPy/\(\alpha\)-Fe₂O₃. The room temperature ac conductivity (\(\sigma\)_ac) and dielectric constant (\(\epsilon\)^’) against frequency in the range 1 Hz to 40 MHz has measured using computer control impedance analyzer. The increment in ac conductivity (\(\sigma\)_ac) of CP and all its composites with rise in frequency assigned the quantum mechanical tunneling (QMT) in all materials under the present study and shows their polycrystalline disorder (amorphous and crystalline) structure. The IR bands, structure, morphology, \(\sigma\)_ac and \(\epsilon\)’ shows dependence on type of oxidant, dopant and wt% of added MO. Oxidants and dopants show the remarkable and intense effect on the frequency response of ac conductivity and dielectric constant of the composites.

The principal characteristic of tropical regions is that the torrential rain occurs almost throughout the year. As a result of this torrential rain, the signals of these areas get attenuated causing disruption in transmitting important messages from a transmitter to a receiver. So the people of these regions face a lot of obstacles in their field of wireless communication. To overcome these obstacles many researchers and developers have been trying heart and soul for a long time by using 5G communication. But no fruitful result has yet been obtained for this purpose. So the goal of this work is to remove these obstacles by using diversity techniques through 5G communication. To achieve the desired result multiple-input and multiple-output (MIMO) technique has been adopted as an antenna diversity technique and here this technique has been used in the communication link model designed for 5G communication for tropical regions. Here a link budget for the designed communication link model has been laid down to increase the signal power and signal to noise ratio (SNR) at the receiver.  The link budget depends on different parameters and these parameters have been demonstrated in this work. In this work an experimental data sheet has also been adopted to achieve the desired result of the link budget.