Development of Three-Stage Bioaerosol Sampler for Size-Selective Sampling

In this study, a three-stage bioaerosol sampler with a sampling flow rate of 170 L/min was designed and fabricated for sampling the bioaerosols released during human breathing and coughing, and its performance was evaluated. The sampler was constructed using a cyclone separator with a cutoff size of 2.5 µm as a preseparator, a multi-nozzle virtual impactor with a cutoff size of 0.34 µm as an aerosol concentrator, and a BioSampler, which is a commercial product, for collecting bioaerosols in a collection fluid. The collection efficiency of the sampler was evaluated through simulations and experiments. Only particles with sizes of 0.1-4 µm were selectively collected in the collection fluid. Bacteriophage bioaerosols were sampled using the developed sampler and ACD-200 Bobcat sampler, which is a commercial product. The amounts of collected bacteriophages were compared using the polymerase chain reaction (PCR) technique. The sampling performance of the developed sampler was similar to that of the ACD-200 Bobcat sampler. Moreover, the developed sampler showed its ability to sample bioaerosols of a specific size-range and collect them directly in a collection fluid for the PCR analysis. Therefore, the developed sampler is expected to be useful for indoor environmental monitoring by effectively sampling the bioaerosols released indoors during human breathing and coughing.

Step Surface Profile Measurement Based on Fringe Projection Phase-Shifting Using Selective Sampling

Fringe projection is a non-contact optical method that is widely used in the optical precision measurement of complex stepped surfaces. However, the accuracy of the fringe phase extraction employed has a direct impact on the measurement precision of the surface shape. Where phase-shifting measurement is used, the classical equal step phase extraction algorithm can only be used to measure simple and smooth surfaces, and leads to measurement errors on complex stepped surfaces, which affects the accuracy of the phase extraction. In addition, the iterative process lasts for a long time, resulting in a low efficiency. This paper proposes a step-by-step phase-shifting extraction algorithm based on selective sampling to measure the contour of the stepped surface. Firstly, the fringe pattern is sampled at equal intervals to reduce the iterative calculation time. Finally, the accurate measurement phase is calculated by the alternating iteration method. The phase extraction accuracy and iteration times are compared in experimental measurements between classical iterative algorithms such as four-step phase-shifting algorithms and the variable phase shift phase interpolation algorithm based on selective sampling. It is shown that the variable frequency phase-shifting extraction algorithm based on selective sampling has a shorter operation time, smaller error, and higher accuracy than the traditional iterative algorithm in fringe projection measuring complex stepped surfaces.

Range Restriction affects Factor Analysis: Normality, Estimation, Fit, Loadings, and Reliability

A sample suffers range restriction (RR) when its variance is reduced comparing to its population variance and, in turn, it fails representing such population. If the RR occurs over the latent factor, not directly over the observed variable, the researcher deals with an indirect RR, common when using convenience samples. This work explores how this problem affects different outputs of the factor analysis: multivariate normality (MVN), estimation process, goodness-of-fit, recovery of factor loadings, and reliability. In doing so, a Monte Carlo study was conducted. Data were generated following the linear selective sampling model, simulating tests varying their sample size (N = 200 and 500 cases), test size (J = 6, 12, 18, 24 items), loading size (L = .50, .70, and .90) and restriction size (from R = 1, .90, .80, and so on till .10 selection ratio). Our results systematically suggest that an interaction between decreasing the loading size and increasing the restriction size affects the MVN assessment, obstructs the estimation process, and leads to an underestimation of the factor loadings and reliability. However, most of the MVN tests and most of the fit indices employed were nonsensitive to the RR problem. We provide some recommendations to applied researchers.

Extended Pre-Processing Pipeline For Text Classification: On the Role of Meta-Features, Sparsification and Selective Sampling

Pipelines for Text Classification are sequences of tasks needed to be performed to classify documents. The pre-processing phase of these pipelines involves different ways of manipulating documents for the learning phase. This Master Thesis introduces three new steps into the traditional pre-processing phase: 1) Meta-Features Generation; 2) Sparsification; and 3) Selective Sampling. Our experimental results, based on more than 5.600 measurements, show that our proposal can achieve significant gains in effectiveness when compared to the traditional TF-IDF representation (up to 52%) and word embeddings (up to 46%), at a much lower cost (9.7x faster). Our Master Thesis also includes a thorough and rigorous evaluation of the trade-offs between cost and effectiveness associated with the introduction of these new steps into the pipeline, as well as a comprehensive comparative experimental evaluation of many alternatives. This thesis falls under the topics of (i) Document Management and Classification, (ii) Information Retrieval Models and Techniques, (iii) and Text Database of the SBBD Call for Papers.

Parental Views on the Lives of Preschool Children in the Covid-19 Pandemic Process

This study aims to investigate the parental views of pre-school children during the Covid 19 pandemic and is conducted using a basic qualitative research design from qualitative research methods. In the study, parents of children attending pre-school institution were identified through criterion sampling techniques from non-selective sampling methods. The study prepared a semi-structured interview form for parents with children attending pre-school institution as an instrument for data collection. The data from the semi-structured interview form was collected through online interviews with parents whose children attend the pre-school facility. As a result of the study, parents indicated that during the pre-school children's pandemic process, there were more activities with family members at home, the children spent more time with technological devices, terms such as pandemic, diseases, and viruses were frequently used in their daily conversations, and their negative, boring, and aggressive behaviors increased. It was also noted that children were sleeping and waking up later during this time, thus changing their sleep patterns. Another finding observed by the parents was that irregular eating habits increased in the children's eating behavior. It was observed by the parents that children were washing their hands more frequently than before the pandemic. Another finding of the study was that children spoke with longing about their school life due to the disruption of personal instruction in schools.

Strategi Perbaikan Implementasi Manajemen Keselamatan dan Kesehatan Kerja (K3) TPAS Wisata Edukasi Talangagung Kabupaten Malang

The operation of the Talangagung Edu-Tourism Landfill applies a sanitary landfill system, which requires a workforce to operate optimally. These workers may be exposed to work accidents and occupational diseases when the Landfill is operating, which come from various sources of OHS hazards. Efforts to reduce the risk of work accidents and occupational diseases consist of managing OHS in the working environment of the Talangagung Edu-Tourism Landfill. The goal of this study is to evaluate the application and provide recommendations to improving the application of OHS management at the Edu-Tourism Landfill in Talangagung. Thus, the Talangagung Edu-Tourism Landfill can maximize the volume of waste and educational tourism facilities. This study involved 16 respondents who were divided into workers and decision-makers by selective sampling in the operation of the Talangagung Edu-Tourism Landfill with data collection by observation, interviews, and questionnaires. The results of this study show that the Talangagung Edu-Tourism Landfill has implemented OHS management but the need to formulate new OHS management, to achieve maximum results. The priority strategy in efforts to improve OHS management is to "enhance awareness of OHS management" where there is a plan to implement the strategy to facilitate implementation of the strategy in the work environment.