Motivation, Background, and Objective:

Photoacoustic imaging is a non-ionizing imaging technique that provides functional and structural information about imaging targets with optical contrast and ultrasound resolution. Thus, it is widely utilized in the medical field. However, in recent years, photoacoustic imaging techniques have been used in industrial applications as non-distractive testing such as surface crack detection. However, the photoacoustic system cost and the time consumption for scanning and imaging reconstruction limit using it in non-destructive testing. Therefore, in this study, low-cost photoacoustic equipment with machine learning technique will be investigated in surface crack detection. This investigation reduces the system complexity and the time consumption for detection compared with that when photoacoustic imaging techniques are used.

Statement of Contribution/Methods:

A piece of black plastic with four surface cracks in a water tank was used as a phantom. The width of each crack was almost 1mm. The photoacoustic emissions were generated from this phantom using a pulse laser diode (PLD) (905D5S3J08X). The width of each firing laser pulse was 100 nm. In addition, the output optical energy and wavelength of this PLD were 3 micro-J and 905 nm respectively. In this experiment, photoacoustic emissions were acquired by using an open-source ultrasound board with one element ultrasound transducer (C310-SU). The centre frequency and bandwidth of this transducer were 5MHz and 90% of the centre frequency respectively. The scanning step of the ultrasound transducer in the lateral direction was 0.1 mm. The received photoacoustic emission for each scanning point was averaged 10 times before using it to improve the SNR of the received photoacoustic signal. In this experiment, 1131 photoacoustic signals were acquired from a cracked place and 4522 photoacoustic signals were acquired from an uncracked place. These received signals were converted to spectrogram images before using them in the machine learning model. In this study, a Convolutional Neural Network (CNN) classification model was used for detecting the presence of cracks in the surfaces. The dataset was randomly split into two independent parts with 80% and 20% for training and testing, respectively.

Results, Discussion, and Conclusions:

The offline prediction accuracy of this model was 97%. This accuracy makes the system capable of performing real-time detection for the crack. When compare this machine learning detection technique with the imaging technique, the machine learning technique reduces the complexity of the system. This is because one scanning line is used as input to the machine learning model, unlike the imaging technique that needs multiple scanning lines to reconstruct the photoacoustic image. The acquisition of multiple scanning lines is time consuming if one single element ultrasound transducer is used. In addition, the cost of the imaging system will be expensive if a multiple element ultrasound transducer is used. Moreover, when a machine learning technique is used, different levels of cracks can be detected. This is unlike the imaging technique that is affected by the contrast level of imaging targets.

The rise of artificial intelligence (AI) has provoked polarized reactions, from being hailed as the unavoidable way for diverse new opportunities to those that consider it another end-of-the-world crisis, perhaps feeded by many fiction works referring to how when artificial intelligence becomes dominant, one of its logic-based decision will be the extermination of humankind (e.g., to preserve the planet).

Most users will see artificial intelligence as a tool with potentialities and risks. Trying to contribute to this discussion, we attempt to assess the use of artificial intelligence in relation to a specific question that can be considered relatively obscure in general terms but with some relevance in our research area.

We asked "What is darapskite?" (literally) to around twenty Android AI apps.

Darapskite is an hydrated salt mineral, which, as shown by the results obtained with search engines such as Google, Yahoo, Bing or Duckduckgo, has an ideal chemical formula with sodium, nitrate and sulfate (besides water), named after Ludwig Darapsky and initially described in Chilean nitrate deposits.

The answers from the vast majority of AI apps were wrong. One app described darapskite as a crypto currency but the most mortifying answers were those that correctly refer to darapskite as a mineral and then presented wrong information about it, errors that showed a significant diversity. There were mistakes in relation to the chemical composition, the date of darapskite definition, the defining locality, the origin of the name, the economic value, the applications and the geological context where darapskite is found.

These results seem to support one of the main charges leveled against artificial intelligence; these apps might be, to use an American cliché, "making things up".

In a kind of analogy with the intersectionality framework used in the social sciences, this could cause especially significant impacts on less skeptical, more socially isolated, poorer students of less recondite study areas, with the risk of contributing to an academic gap in relation to more critically-minded, socially connected, richer students from more prominent areas of knowledge.

This article presents a comprehensive review of control approaches for industrial robotic manipulators, focusing on research conducted from 2020 onwards. The efficient functioning of robotic arms and successful task completion necessitate effective control strategies. Addressing real-world challenges, such as dynamic system variations due to environmental changes and unknown disturbances, remains crucial. To tackle these challenges, robust control strategies, including PID, H∞, and Model Predictive Control, are thoroughly surveyed. Commercially employed trajectory planning techniques for manipulators are also extensively discussed. The issue of chattering in control systems is highlighted, and various methods to mitigate it are presented. Ultimately, the paper concludes by providing valuable insights into prospective areas for future research, with the aim of enhancing the capabilities and performance of control strategies for industrial robotic manipulators. This study offers valuable knowledge to advance the field of robotic automation in Industry 4.0, fostering the development of efficient and intelligent manufacturing processes.

This study is dedicated to the investigation and comparison of the kinetics of foam stability of protein foaming agents based on hydrolysates of solid keratin. The work utilized ready-made hydrolysates based on sodium hydroxide and a mixture of sodium hydroxide with calcium hydroxide for the synthesis of foaming agents. The synthesis was carried out according to the author's methodology.

Among the indicators studied were foam multiplication, foam specific weight, foam stability over time, and average foam stability reduction rate. Experiments were conducted with various concentrations and ratios of components at constant temperature, pressure, and pH values, as well as mixing speed, mixing time, and observation time. It is hypothesized that protein foaming agents based on hydrolysates of solid keratin using a mixture of hydroxides will not be able to achieve optimal values in the kinetics of foam stability. In contrast, protein foaming agents based on hydrolysates of solid keratin using sodium hydroxide individually have high potential foaming properties and, consequently, good foam stability kinetics indicators.

The results of this study may be useful in the development of new synthesis methods for protein foaming agents with optimal foaming properties or for improving those that already exist. The research itself and the products obtained during it – protein foaming agents, are mainly aimed at expanding the industrial sphere of human activity. This may also have practical applications in other areas such as the food industry, cosmetology, medicine, and others.

Electronic structures and molecular dynamics of gadolinium-doped formamidinium lead iodine (FAPbI₃) perovskite crystal were studied for improving the photovoltaic performance with stability. The band structure, partial density of state, electron density distribution, enthalpy, kinetic energy, molecular dynamics were expected by first-principles calculation. The narrow band dispersion, delocalization of 5d, 4f orbital of gadolinium, 6p orbital of lead ion, 5p orbital of iodine ion near valence and conduction band states promoted the charge transfer between 5d orbital of gadolinium ion and 6p orbital of lead ion, expecting increase of carrier mobility related with short circuit current density as the photovoltaic performance. Addition of gadolinium ion into the crystal caused the slight distortion in the crystal field, stabilizing the crystal while suppression of the decomposition with desorption and diffusion of the ions in the crystal. The stability of the performance would be explained by the thermodynamic characteristics The enthalpy and kinetic energy based on the molecular dynamics indicates stabilization of the gadolinium-doped perovskite crystal with slight distortion of coordination structure, as compared with that of the FAPbI₃ perovskite crystal. Addition of gadolinium ion into the perovskite crystal supported the stability of the photovoltaic performance. The calculation prediction expect that the gadolinium-doped FAPbI₃ perovskite crystal have great potential to apply for the industry product of the photovoltaic devices with the photovoltaic performance.

Knowingly or unknowingly we are surrounded by many creatures which are specialized in building amazing structures with great finesse. It’s really wonderful to see how such tiny brains coordinate with each other to create perfect structure which is perhaps impossible for humans. On similar lines, the present study describes the nest architecture of tropical hornet, Vespa affinis built across several locations in Jalpaiguri district of West Bengal, India. Mature nests are roughly pear shaped, broadening from the top to truncate base. The architecture of the nest is in the pattern of a spiral staircase with a central and several auxiliary petioles supporting each of the comb layers. 2 large usually round entrance holes along with 6-7 small holes were also seen on the walls of the nest. Strikingly the hypertrophy of the nest envelope above the combs into a prominent roof cone with cellular structure is observed. Hardening of the nest texture and extensive papering over of the cells in the initial comb layers, thereby reducing their reutilization forms an essential feature of their nest. Several morpho-metric measurement of a typical nest (with 7 comb layers) from the study site was conducted. Each comb layers of the nests showed a rough bimodality of cell-diameter, with peaks at about 0.85 and 1.0 mm. The maximum number of occupied cells in the centre most stages of the nest (i.e. Comb layer 3) probably support the maximum number of brood members. The largest number of auxiliary petioles along with the tree branch provides greatest protection to the brood in this layer. Besides the highest number of petioles, the maximum number of unoccupied cells in comb layer 2 and 4 also provides extra protection to the developing brood in the comb layer 3. A decrease in the rate of nest building in the final stages (i.e. comb layer 6 and 7) is evident by the decrease in the number of cells in these layers.

Housing attributes to the physical structure that provides shelter, social services with hygienic neighborhood to fulfil the essential needs of the people. Housing factors have shown to have an effect on an individual’s status of physical, mental, social and economic well-being. Indoor environmental factors such as crowding, environmental tobacco smoke, biofuel, dampness, house dust mites, temperature, age of building, pets, indoor plants affect the wellbeing and productivity of the occupants. A literature review was done on studies of housing conditions and health outcomes conducted in India and abroad from 1999 to 2020. The studies assessed the housing quality by self-reported questionnaire administered through postal, face-to-face or internet. Visual signs and non-volumetric method were used to assess indoor air quality and housing conditions, while health of residents was assessed by self-reported questionnaire, or SF-36 questionnaire. Studies conducted in United States of America, Europe, United Kingdom, Middle East, Africa and Australasia revealed that factors effecting health conditions were ventilation, dampness, presence of molds, overcrowding, house dust mite allergens, age and renovation of buildings and these factors showed association with respiratory illness, cold, cough, asthma, conjunctivitis, atopic dermatitis and ear infection. However, studies in India revealed that lack of proper ventilation, use of traditional fuels, crowding and poor hygienic conditions are the main factors associated with acute respiratory infection, asthma, tuberculosis, cardiovascular disease and lung cancer. Thus, the review highlights that there is a need to improve housing conditions in India to enable the people to lead a healthy and productive life.

The crisis of safe drinking water is a major global issue, with millions of people around the world lacking access to clean and potable water. This is due to a range of factors, including poor infrastructure, environmental degradation and natural disasters.As a result, there is a growing need for technologies that can purify water and make it harmless for consumption. Water filters and other purification technologies are becoming increasingly important in solving this issue, as they can remove contaminants such as bacteria, viruses, and heavy metals from water.The thesis explores the comparative analysis of five types of water purification technologies. Water is commonly consumed in Bangladesh from sources including WASA tap water, boiled water,water from reverse osmosis filter,WASA water booth, candle filter, pureit filter.The study examines the effectiveness and competence of each technology to provide clean and safe drinking water. The background and motivations of the study include the large number of people in Bangladesh who lack access to safe drinking water, the importance of water filtration in preventing water borne diseases and the need for economic and environment friendly water purifying systems. The thesis aims to promote the use of effective, affordable and sustainable water purification systems and to apprise the readers of the identified drawbacks in certain water purification technologies.The results showed that micro-organism, iron and lead concentration level of WASA tap water exceeded the limit set by Bangladesh standards. Water collected from water vending machine contained micro-organisms and boiled water contained considerable level of iron.All the other water purifying technologies could effectively remove contaminants from water.

This research paper addresses the issue of enhancing the operational availability of NPC three-level converter-based high voltage direct current (HVDC) transport systems during alternating current (AC) grid fault conditions. During short-circuit faults in power transmission lines, voltage sags can occur, causing fluctuations in the DC link voltage of converter systems. These voltage sags have the potential to induce reversed power flow and lead to the tripping of VSC-HVDC transmission systems. The objective of this paper is to develop a nonlinear control technique that investigates the fault ride-through (FRT) capability of VSC-HVDC transmission system characteristics during voltage sag events. To achieve this, we conduct semi-experimental investigations using Processor-in-the-loop (PIL) simulations and analyze the results. Symmetrical and asymmetrical voltage sag events with different remaining voltages are applied to an AC grid, and their effects are observed for varying durations.

The proposed nonlinear control technique aims to mitigate the impact of voltage sags on the operational availability of HVDC transport systems. By analyzing the semi-experimental results, we aim to gain insights into the FRT capability of the VSC-HVDC transmission system. This research contributes to the field by providing a comprehensive understanding of the behavior and performance of HVDC systems under AC grid fault conditions. The findings of this study show the effectiveness and high efficiency of the proposed nonlinear control strategy and ensure uninterrupted power transmission even in the presence of voltage sags caused by AC grid faults.

Global warming is a pressing issue that has captured significant attention in recent times. However, it is important to note that temperature variations can be observed even within close geographical locations. These variations can be attributed to the diverse characteristics of different surfaces and their respective heat absorption and reflection capabilities during the day. Furthermore, temperature irregularities are also evident during the night. The factors contributing to these temperature variations include elevation, roughness, color, and material composition of the surfaces. For instance, urban areas characterized by concrete and asphalt surfaces tend to absorb and retain more heat, resulting in higher temperatures compared to rural regions with greater vegetation cover and natural surfaces. This phenomenon is commonly referred to as the urban heat island effect. The research focuses on pavement, buildings, and vegetation cover for surface analysis. In addition to surface characteristics, relative humidity also contributes to temperature fluctuations. Variations in humidity levels can be observed both during the day and at night, and it plays a significant role in influencing local temperatures. Research efforts have predominantly focused on examining the irregularity in trends associated with specific locations and their corresponding surface types. Moreover, understanding the intricate relationship between relative humidity and temperature during both diurnal and nocturnal periods has been a crucial aspect of these studies. Surface features, population, urbanization, and land use contribute to the discrepancies in the regular trend. The result of these investigations presents these irregular trends specific to various locations and surface types while also examining the interconnections between relative humidity and temperature within a five-year time span.