Search results for: distributed type-2 fuzzy algorithm
Commenced in January 2007
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Edition: International
Paper Count: 5840

Search results for: distributed type-2 fuzzy algorithm

980 Personal and Social Factors as Barriers to Leisure Walking in Residential Neighborhoods

Authors: Zeinab Aliyas, Diba Mahboubi

Abstract:

Leisure walking is known as one of the most common types of physical activity that perform in purpose of recreation or health, which in turn may affect resident’s health. In the recent years, promoting leisure walking activity in neighborhood areas become as one of the important issues regarding promoting mental and physical health, however; the level of physical inactivity is rising in many societies including Iran. As it was proven that the tendency to walk out of choice is not encouraging among Iranian people. Hence; understanding the main concern of residents regarding walking activity in their neighborhoods can help in increasing the tendency to do leisure activity among residents. Built environment, social and individual factors are known as the main factors that affect decision to walk, in this regard, the study aimed to investigate the influence of personal and social factors that prevent residents to walk for recreation or exercise in their neighborhoods. Hence the fear of crime and personal barriers were examined in the current research as social and personal factors respectively. To collect the required data, 500 questionnaires by using systematic sampling were distributed from March to May 2016 in four residential neighborhoods of Bandar Abbas in Iran out which 411 questionnaire turned out to be qualified to be used in the study. The Smart-PLS was used to analyze the data. The findings of the study revealed that personal and fear of crime both have significant influence on the level of recreation and exercise walking in the neighborhood areas. The study found that fear of crime has the higher influence on exercise and recreational walking behavior in comparison to individual factors. It was revealed that social factors such as fear of crime in the neighborhoods might be more important than the personal reason for walking optionally in the surrounding environment. The finding of this study can help urban and health researcher to know the significant influence of fear of crime and individual attitudes on the level of leisure walking activity, in addition, the findings of the study suggest that urban planners and designers, as well as public health promoters, need to highly consider the contribution of neighborhoods' social environment variables as well as individual variables to promote walking behavior changes among adult population.

Keywords: exercise walking, fear of crime, neighborhood, personal barriers, recreation walking

Procedia PDF Downloads 165
979 Finite Volume Method for Flow Prediction Using Unstructured Meshes

Authors: Juhee Lee, Yongjun Lee

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In designing a low-energy-consuming buildings, the heat transfer through a large glass or wall becomes critical. Multiple layers of the window glasses and walls are employed for the high insulation. The gravity driven air flow between window glasses or wall layers is a natural heat convection phenomenon being a key of the heat transfer. For the first step of the natural heat transfer analysis, in this study the development and application of a finite volume method for the numerical computation of viscous incompressible flows is presented. It will become a part of the natural convection analysis with high-order scheme, multi-grid method, and dual-time step in the future. A finite volume method based on a fully-implicit second-order is used to discretize and solve the fluid flow on unstructured grids composed of arbitrary-shaped cells. The integrations of the governing equation are discretised in the finite volume manner using a collocated arrangement of variables. The convergence of the SIMPLE segregated algorithm for the solution of the coupled nonlinear algebraic equations is accelerated by using a sparse matrix solver such as BiCGSTAB. The method used in the present study is verified by applying it to some flows for which either the numerical solution is known or the solution can be obtained using another numerical technique available in the other researches. The accuracy of the method is assessed through the grid refinement.

Keywords: finite volume method, fluid flow, laminar flow, unstructured grid

Procedia PDF Downloads 256
978 Automatic Registration of Rail Profile Based Local Maximum Curvature Entropy

Authors: Hao Wang, Shengchun Wang, Weidong Wang

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On the influence of train vibration and environmental noise on the measurement of track wear, we proposed a method for automatic extraction of circular arc on the inner or outer side of the rail waist and achieved the high-precision registration of rail profile. Firstly, a polynomial fitting method based on truncated residual histogram was proposed to find the optimal fitting curve of the profile and reduce the influence of noise on profile curve fitting. Then, based on the curvature distribution characteristics of the fitting curve, the interval search algorithm based on dynamic window’s maximum curvature entropy was proposed to realize the automatic segmentation of small circular arc. At last, we fit two circle centers as matching reference points based on small circular arcs on both sides and realized the alignment from the measured profile to the standard designed profile. The static experimental results show that the mean and standard deviation of the method are controlled within 0.01mm with small measurement errors and high repeatability. The dynamic test also verified the repeatability of the method in the train-running environment, and the dynamic measurement deviation of rail wear is within 0.2mm with high repeatability.

Keywords: curvature entropy, profile registration, rail wear, structured light, train-running

Procedia PDF Downloads 228
977 ANOVA-Based Feature Selection and Machine Learning System for IoT Anomaly Detection

Authors: Muhammad Ali

Abstract:

Cyber-attacks and anomaly detection on the Internet of Things (IoT) infrastructure is emerging concern in the domain of data-driven intrusion. Rapidly increasing IoT risk is now making headlines around the world. denial of service, malicious control, data type probing, malicious operation, DDos, scan, spying, and wrong setup are attacks and anomalies that can affect an IoT system failure. Everyone talks about cyber security, connectivity, smart devices, and real-time data extraction. IoT devices expose a wide variety of new cyber security attack vectors in network traffic. For further than IoT development, and mainly for smart and IoT applications, there is a necessity for intelligent processing and analysis of data. So, our approach is too secure. We train several machine learning models that have been compared to accurately predicting attacks and anomalies on IoT systems, considering IoT applications, with ANOVA-based feature selection with fewer prediction models to evaluate network traffic to help prevent IoT devices. The machine learning (ML) algorithms that have been used here are KNN, SVM, NB, D.T., and R.F., with the most satisfactory test accuracy with fast detection. The evaluation of ML metrics includes precision, recall, F1 score, FPR, NPV, G.M., MCC, and AUC & ROC. The Random Forest algorithm achieved the best results with less prediction time, with an accuracy of 99.98%.

Keywords: machine learning, analysis of variance, Internet of Thing, network security, intrusion detection

Procedia PDF Downloads 92
976 The Effect of Musical Mobile Usage on the Physiological Parameters and Pain Level During Intestinal Stomaterapy Procedure in Infants

Authors: Hilal Keskin, Gülzade Uysal

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This study was conducted to determine the effect of bedside music mobile use on physiological parameters and pain level during intestinal stomaterapy in infants. The study was carried out with 66 babies (music mobile group: 33, Control group: 33) who were followed in the pediatric surgery and urology unit of Kanuni Sultan Süleyman Training and Research Hospital between December 2018- October 2019. Data were collected using the “Data Collection Form” and “FLACC Pain Scale.” They were evaluated using the appropriate statistical methods in the SPSS 22.0 program. The difference between the descriptive features of music mobile and control group was not significant (p> 0.05) groups are distributed homogeneously. When the in-group results were examined; There was no significant change in the mean values of Hearth Peak Beat (HPB), SpO2 and blood pressure of the infants in the music mobile group during stomaterapy (p>0.05). Body temperature and Face, Leg, Activity, Cry, Consolability (FLACC) Pain Scale scores were found to increase immediately after stomaterapy (p<0.05). It was found that the mean scores of KTA, body temperature and FLACC pain of the babies in the control group increased significantly after the stomaterapy and SpO2 value decreased (p <0,05). After 15 minutes from stomatherapy, KTA, blood pressure, body temperature and FLACC pain scores averaged; although SpO2 value increased, it was determined that it could not reach pre-stomaterapy value. Results between groups; KTA, SpO2, systolic/diastolic blood pressure, body temperature, and FLACC pain score mean values between groups were homogeneous before stomaterapy (p> 0.05). In the control group, a significant increase was found in the mean scores of KTA, body temperature and FLACC pain after stomaterapy compared to the bedside music mobile group, and a significant decrease in SpO2 values (p <0.05). In the control group, the mean body temperature and FLACC pain scores of the infants 15 minutes after stomaterapy were significantly increased and the SpO2 values were significantly lower than the bedside music group (p <0.05). According to the results of the research; The use of bedside music mobile during intestinal stomaterapy was found to be effective in decreasing the physiological parameters and pain level. It can be recommended for use in infants during painful interventions.

Keywords: intestinal stomatherapy, infant, musical mobile, pain, physiological parameters

Procedia PDF Downloads 158
975 Identification of Hepatocellular Carcinoma Using Supervised Learning Algorithms

Authors: Sagri Sharma

Abstract:

Analysis of diseases integrating multi-factors increases the complexity of the problem and therefore, development of frameworks for the analysis of diseases is an issue that is currently a topic of intense research. Due to the inter-dependence of the various parameters, the use of traditional methodologies has not been very effective. Consequently, newer methodologies are being sought to deal with the problem. Supervised Learning Algorithms are commonly used for performing the prediction on previously unseen data. These algorithms are commonly used for applications in fields ranging from image analysis to protein structure and function prediction and they get trained using a known dataset to come up with a predictor model that generates reasonable predictions for the response to new data. Gene expression profiles generated by DNA analysis experiments can be quite complex since these experiments can involve hypotheses involving entire genomes. The application of well-known machine learning algorithm - Support Vector Machine - to analyze the expression levels of thousands of genes simultaneously in a timely, automated and cost effective way is thus used. The objectives to undertake the presented work are development of a methodology to identify genes relevant to Hepatocellular Carcinoma (HCC) from gene expression dataset utilizing supervised learning algorithms and statistical evaluations along with development of a predictive framework that can perform classification tasks on new, unseen data.

Keywords: artificial intelligence, biomarker, gene expression datasets, hepatocellular carcinoma, machine learning, supervised learning algorithms, support vector machine

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974 Bayesian Inference for High Dimensional Dynamic Spatio-Temporal Models

Authors: Sofia M. Karadimitriou, Kostas Triantafyllopoulos, Timothy Heaton

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Reduced dimension Dynamic Spatio-Temporal Models (DSTMs) jointly describe the spatial and temporal evolution of a function observed subject to noise. A basic state space model is adopted for the discrete temporal variation, while a continuous autoregressive structure describes the continuous spatial evolution. Application of such a DSTM relies upon the pre-selection of a suitable reduced set of basic functions and this can present a challenge in practice. In this talk, we propose an online estimation method for high dimensional spatio-temporal data based upon DSTM and we attempt to resolve this issue by allowing the basis to adapt to the observed data. Specifically, we present a wavelet decomposition in order to obtain a parsimonious approximation of the spatial continuous process. This parsimony can be achieved by placing a Laplace prior distribution on the wavelet coefficients. The aim of using the Laplace prior, is to filter wavelet coefficients with low contribution, and thus achieve the dimension reduction with significant computation savings. We then propose a Hierarchical Bayesian State Space model, for the estimation of which we offer an appropriate particle filter algorithm. The proposed methodology is illustrated using real environmental data.

Keywords: multidimensional Laplace prior, particle filtering, spatio-temporal modelling, wavelets

Procedia PDF Downloads 400
973 Optimisation of B2C Supply Chain Resource Allocation

Authors: Firdaous Zair, Zoubir Elfelsoufi, Mohammed Fourka

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The allocation of resources is an issue that is needed on the tactical and operational strategic plan. This work considers the allocation of resources in the case of pure players, manufacturers and Click & Mortars that have launched online sales. The aim is to improve the level of customer satisfaction and maintaining the benefits of e-retailer and of its cooperators and reducing costs and risks. Our contribution is a decision support system and tool for improving the allocation of resources in logistics chains e-commerce B2C context. We first modeled the B2C chain with all operations that integrates and possible scenarios since online retailers offer a wide selection of personalized service. The personalized services that online shopping companies offer to the clients can be embodied in many aspects, such as the customizations of payment, the distribution methods, and after-sales service choices. In addition, every aspect of customized service has several modes. At that time, we analyzed the optimization problems of supply chain resource allocation in customized online shopping service mode, which is different from the supply chain resource allocation under traditional manufacturing or service circumstances. Then we realized an optimization model and algorithm for the development based on the analysis of the allocation of the B2C supply chain resources. It is a multi-objective optimization that considers the collaboration of resources in operations, time and costs but also the risks and the quality of services as well as dynamic and uncertain characters related to the request.

Keywords: e-commerce, supply chain, B2C, optimisation, resource allocation

Procedia PDF Downloads 246
972 Multi-Level Air Quality Classification in China Using Information Gain and Support Vector Machine

Authors: Bingchun Liu, Pei-Chann Chang, Natasha Huang, Dun Li

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Machine Learning and Data Mining are the two important tools for extracting useful information and knowledge from large datasets. In machine learning, classification is a wildly used technique to predict qualitative variables and is generally preferred over regression from an operational point of view. Due to the enormous increase in air pollution in various countries especially China, Air Quality Classification has become one of the most important topics in air quality research and modelling. This study aims at introducing a hybrid classification model based on information theory and Support Vector Machine (SVM) using the air quality data of four cities in China namely Beijing, Guangzhou, Shanghai and Tianjin from Jan 1, 2014 to April 30, 2016. China's Ministry of Environmental Protection has classified the daily air quality into 6 levels namely Serious Pollution, Severe Pollution, Moderate Pollution, Light Pollution, Good and Excellent based on their respective Air Quality Index (AQI) values. Using the information theory, information gain (IG) is calculated and feature selection is done for both categorical features and continuous numeric features. Then SVM Machine Learning algorithm is implemented on the selected features with cross-validation. The final evaluation reveals that the IG and SVM hybrid model performs better than SVM (alone), Artificial Neural Network (ANN) and K-Nearest Neighbours (KNN) models in terms of accuracy as well as complexity.

Keywords: machine learning, air quality classification, air quality index, information gain, support vector machine, cross-validation

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971 Breast Cancer Survivability Prediction via Classifier Ensemble

Authors: Mohamed Al-Badrashiny, Abdelghani Bellaachia

Abstract:

This paper presents a classifier ensemble approach for predicting the survivability of the breast cancer patients using the latest database version of the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute. The system consists of two main components; features selection and classifier ensemble components. The features selection component divides the features in SEER database into four groups. After that it tries to find the most important features among the four groups that maximizes the weighted average F-score of a certain classification algorithm. The ensemble component uses three different classifiers, each of which models different set of features from SEER through the features selection module. On top of them, another classifier is used to give the final decision based on the output decisions and confidence scores from each of the underlying classifiers. Different classification algorithms have been examined; the best setup found is by using the decision tree, Bayesian network, and Na¨ıve Bayes algorithms for the underlying classifiers and Na¨ıve Bayes for the classifier ensemble step. The system outperforms all published systems to date when evaluated against the exact same data of SEER (period of 1973-2002). It gives 87.39% weighted average F-score compared to 85.82% and 81.34% of the other published systems. By increasing the data size to cover the whole database (period of 1973-2014), the overall weighted average F-score jumps to 92.4% on the held out unseen test set.

Keywords: classifier ensemble, breast cancer survivability, data mining, SEER

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970 Delineation of Subsurface Tectonic Structures Using Gravity, Magnetic and Geological Data, in the Sarir-Hameimat Arm of the Sirt Basin, NE Libya

Authors: Mohamed Abdalla Saleem, Hana Ellafi

Abstract:

The study area is located in the eastern part of the Sirt Basin, in the Sarir-Hameimat arm of the basin, south of Amal High. The area covers the northern part of the Hamemat Trough and the Rakb High. All of these tectonic elements are part of the major and common tectonics that were created when the old Sirt Arch collapsed, and most of them are trending NW-SE. This study has been conducted to investigate the subsurface structures and the sedimentology characterization of the area and attempt to define its development tectonically and stratigraphically. About 7600 land gravity measurements, 22500 gridded magnetic data, and petrographic core data from some wells were used to investigate the subsurface structural features both vertically and laterally. A third-order separation of the regional trends from the original Bouguer gravity data has been chosen. The residual gravity map reveals a significant number of high anomalies distributed in the area, separated by a group of thick sediment centers. The reduction to the pole magnetic map also shows nearly the same major trends and anomalies in the area. Applying the further interpretation filters reveals that these high anomalies are sourced from different depth levels; some are deep-rooted, and others are intruded igneous bodies within the sediment layers. The petrographic sedimentology study for some wells in the area confirmed the presence of these igneous bodies and defined their composition as most likely to be gabbro hosted by marine shale layers. Depth investigation of these anomalies by the average depth spectrum shows that the average basement depth is about 7.7 km, while the top of the intrusions is about 2.65 km, and some near-surface magnetic sources are about 1.86 km. The depth values of the magnetic anomalies and their location were estimated specifically using the 3D Euler deconvolution technique. The obtained results suggest that the maximum depth of the sources is about 4938m. The total horizontal gradient of the magnetic data shows that the trends are mostly extending NW-SE, others are NE-SW, and a third group has an N-S extension. This variety in trend direction shows that the area experienced different tectonic regimes throughout its geological history.

Keywords: sirt basin, tectonics, gravity, magnetic

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969 Interrelationship of Socio-Demographic Factors, Health Belief Dimensions and Compliance to Measles Vaccination among Filipino Mothers

Authors: Beryl Rene R. Lopez, Lesley Anne M. Lipat, Rhogene Barbette C. Lirio, Laurice Joy H. Llanes, Karl Philippe M. Llapitan, Einstein James R. Lopez, Socorro S. GuanHing

Abstract:

Background: Measles remain as one of the most common childhood diseases despite the availability of the vaccine that is safe and cost-effective. Because of morbidity and mortality associated with the recent measles outbreak in the Philippines, there is an increasing concern from the health care professionals. Objective: The purpose of this study is to determine the relationship between the compliance of Filipino mothers to measles vaccination and their health beliefs when grouped according to the given socio-demographic factors using a researcher-made questionnaire. Research Methodology: This research utilized the descriptive-correlational research design. With the use of purposive sampling technique, the study involved 200 Filipino mothers aged 18 years old and above excluding those who are healthcare professionals with children aged 2-3 years old with either urban or rural as their settlements. Pre-testing was done prior to the actual data gathering. A questionnaire composed of 26 items involving socio-demographic, compliance, and health beliefs was distributed to the sample population. Statistical analysis was done with the use of Exploratory Factor Analysis (EFA) for the first research question and Structural Equation Model (SEM) for the second research question. Results: Four dimensions were generated with the use of EFA namely: Vulnerability-Oriented Beliefs (VOB), Knowledge-Oriented Beliefs (KOB), Accessibility-Oriented Beliefs (AOB), and Outcomes-Oriented Beliefs (OOB). These were then correlated with the mothers’ socio-demographic factors (age, educational attainment, the area of residence, the number of children, and family income) and their compliance to the measles vaccination schedule. Results showed significant and direct relationships between area of residence and compliance, family income and compliance, KOB and compliance, education and KOB, KOB and VOB, KOB and OOB, AOB and KOB, AOB and OOB, AOB and VOB, and lastly, OOB and VOB. Conclusion: The Knowledge – Oriented Belief dimension greatly influence compliance to measles vaccination. Other determinants of compliance like the area of residence, educational attainment, and family income significantly increase the Filipino mothers’ likelihood of compliance to measles vaccination, which have implications to health education.

Keywords: socio-demographic, health beliefs, compliance, measles vaccination

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968 The Study on How Outward Direct Investment of Chinese MNEs to European Union Area Affect the Domestic Industrial Structure

Authors: Nana Weng

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From 2008, Chinese Foreign Direct Investment flows to the European Union continued its rapid rise. Currently, the industrial structure adjustment in developing countries has also been placed on the international movement of factors of production. Now China economy is in an important period of transformation on industrial structure adjustment. Under the international transfer of industry background, the adjustment of industrial structure upgrading and sophistication are the key elements of a successful economic transformation. In order to achieve a virtuous cycle of foreign investment patterns and optimize the industrial structure of foreign direct investment as well, the research on the positive the role of the EU direct investment and how it impact China’s industrial structure optimization and upgrading is of great significance. In this paper, the author explained how the EU as an investment destination is different with the United States and ASEAN. Then, based on the theory of FDI and industrial structure and combining the four kinds of motives of China’s ODI in EU, this paper explained the impact mechanism which has influenced China domestic industrial structure primarily through the Transfer effect, Correlation effect and Competitive effect. On the premise that FDI activities do affect the home country’s domestic industrial structure, this paper made empirical analysis with industrial panel data. With the help of Gray Correlation Method and Limited Distributed Lags, this paper found that China/s ODI in the EU impacted the tertiary industry strongly and had a significant positive impact, particularly the manufacturing industry and the financial industry. This paper also pointed out that Chinese MNEs should realize several issues, such as pay more attention to high-tech industries so that they can make the best use of reverse technology spillover. When Chinese enterprises ‘go out,' they ought to keep in mind that domestic research and development capital contribution can make greater economic growth. Finally, based on theoretical and empirical analysis results, this paper presents the industry choice recommendations in the future of the EU direct investment, particularly through the development of the proper rational industrial policy and industrial development strategic to guide the industrial restructuring and upgrading.

Keywords: china ODI in european union, industrial structure optimization, impact mechanism, empirical analysis

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967 Effect of Dietary Sour Lemon Peel Essential Oil on Serum Parameters in Rainbow Trout (Oncorhynchus mykiss) Fingerlings against Deltamethrin Stress

Authors: Maryam Amiri Resketi, Sakineh Yeganeh, Khosro Jani Khalili

Abstract:

The aim of this study was to investigate the effect of dietary lemon peel essential oil (Citrus limon) on serum parameters and liver enzyme activity of rainbow trout (Oncorhynchus mykiss) was exposed to deltamethrin. The 96-hour lethal concentrations of the toxin on rainbow trout (Oncorhynchus mykiss), was determined according to standard procedures O.E.C.D in static (Static). 96-hour LC50 was obtained 0.0082 mg/l by using statistical methods Probit program version. The maximum allowable concentration of deltamethrin was calculated 0.00082 mg/l in natural environment and was used for this experiment. Eight treatments were designed based on 3 levels of lemon essential oil 200, 400 and 600 mg/kg and 2 levels of deltamethrin 0 and 0.00082. Rainbow trout with an average weight of 95.14 ± 3.8 g were distributed in 300-liter tanks and cultured for eight weeks. Fish were fed in an amount of 2% of body weight. Water changes were done on a daily basis (90 percent of the tank). About the tanks containing 10 % deltamethrin, after dewatering, suitable concentration of toxin was added to water. At the end of the test, serum biochemical parameters (total protein, albumin, glucose, cholesterol, and triglycerides) and liver enzymes (ALP, AST, ALT and LDH) were evaluated. In treatments without and with toxin, increasing 400 mg/kg oil increased total protein and albumin levels and lower cholesterol and triglycerides were observed (p < 0.05). Rise to the level of 400 mg/kg of lemon peel essential oil treatments contain pesticides, reduced the amount of enzymes ALP, ALT and LDH compared to treatment of toxin-free lemon peel essential oil (p < 0.05). The results showed that usage of lemon peel essential oil in fish diet can increase the immune system parameters and strengthen it with strong antioxidant activity followed by reducing the effect of deltamethrin on the immune system of fish and effective dose can prevent the adverse effects of toxin due to the weakening of the fish immune system at the time of toxic pollutant entrance in fish farms.

Keywords: deltamethrin, Oncorhynchus mykiss, LC5096h, lemon peel (citrus limon) essential oil, serum parameters, liver enzymes

Procedia PDF Downloads 168
966 Association between Attention Deficit Hyperactivity Disorder Medication, Cannabis, and Nicotine Use, Mental Distress, and Other Psychoactive Substances

Authors: Nicole Scott, Emily Dwyer, Cara Patrissy, Samantha Bonventre, Lina Begdache

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Across North America, the use and abuse of Attention Deficit Hyperactivity Disorder (ADHD) medication, cannabis, nicotine, and other psychoactive substances across college campuses have become an increasingly prevalent problem. Students frequently use these substances to aid their studying or deal with their mental health issues. However, it is still unknown what psychoactive substances are likely to be abused when college students illicitly use ADHD medication. In addition, it is not clear which psychoactive substance is associated with mental distress. Thus, the purpose of this study is to fill these gaps by assessing the use of different psychoactive substances when illicit ADHD medication is used; and how this association relates to mental stress. A total of 702 undergraduate students from different college campuses in the U.S. completed an anonymous survey distributed online. Data were self-reported on demographics, the use of ADHD medications, cannabis, nicotine, other psychoactive drugs, and mental distress, and feelings and opinions on the use of illicit study drugs were all included in the survey. Mental distress was assessed using the Kessler Psychological Distress 6 Scale. Data were analyzed in SPSS, Version 25.0, using Pearson’s Correlation Coefficient. Our results show that use of ADHD medication, cannabis use (non-frequent and very frequent), and nicotine use (non-frequent and very frequent), there were both statistically significant positive and negative correlations to specific psychoactive substances and their corresponding frequencies. Along the same lines, ADHD medication, cannabis use (non-frequent and very frequent), and nicotine use (non-frequent and very frequent) had statistically significant positive and negative correlations to specific mental distress experiences. As these findings are combined, a vicious loop can initiate a cycle where individuals who abuse psychoactive substances may or may not be inclined to use other psychoactive substances. This may later inhibit brain functions in those main areas of the brain stem, amygdala, and prefrontal cortex where this vicious cycle may or may not impact their mental distress. Addressing the impact of study drug abuse and its potential to be associated with further substance abuse may provide an educational framework and support proactive approaches to promote awareness among college students.

Keywords: stimulant, depressant, nicotine, ADHD medication, psychoactive substances, mental health, illicit, ecstasy, adrenochrome

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965 Analysis of Social Factors for Achieving Social Resilience in Communities of Indonesia Special Economic Zone as a Strategy for Developing Program Management Frameworks

Authors: Inda Annisa Fauzani, Rahayu Setyawati Arifin

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The development of Special Economic Zones in Indonesia cannot be separated from the development of the communities in them. In accordance with the SEZ's objectives as a driver of economic growth, the focus of SEZ development does not only prioritize investment receipts and infrastructure development. The community as one of the stakeholders must also be considered. This becomes a challenge when the development of an SEZ has the potential to have an impact on the community in it. These impacts occur due to changes in the development of the area in the form of changes in the main regional industries and changes in the main livelihoods of the community. As a result, people can feel threats and disturbances. The community as the object of development is required to be able to have resilience in order to achieve a synergy between regional development and community development. A lack of resilience in the community can eliminate the ability to recover from disturbances and difficulty to adapt to changes that occur in their area. Social resilience is the ability of the community to be able to recover from disturbances and changes that occur. The achievement of social resilience occurs when the community gradually has the capacity in the form of coping capacity, adaptive capacity, and transformative capacity. It is hoped that when social resilience is achieved, the community will be able to develop linearly with regional development so that the benefits of this development can have a positive impact on these communities. This study aims to identify and analyze social factors that influence the achievement of social resilience in the community in Special Economic Zones in Indonesia and develop a program framework for achieving social resilience capacity in the community so that it can be used as a strategy to support the successful development of Special Economic Zones in Indonesia that provide benefits to the local community. This study uses a quantitative research method approach. Questionnaires are used as research instruments which are distributed to predetermined respondents. Respondents in this study were determined by using purposive sampling of the people living in areas that were developed into Special Economic Zones. Respondents were given a questionnaire containing questions about the influence of social factors on the achievement of social resilience. As x variables, 42 social factors are provided, while social resilience is used as y variables. The data collected from the respondents is analyzed in SPSS using Spearman Correlation to determine the relation between x and y variables. The correlated factors are then used as the basis for the preparation of programs to increase social resilience capacity in the community.

Keywords: community development, program management, social factor, social resilience

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964 Understanding the Basics of Information Security: An Act of Defense

Authors: Sharon Q. Yang, Robert J. Congleton

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Information security is a broad concept that covers any issues and concerns about the proper access and use of information on the Internet, including measures and procedures to protect intellectual property and private data from illegal access and online theft; the act of hacking; and any defensive technologies that contest such cybercrimes. As more research and commercial activities are conducted online, cybercrimes have increased significantly, putting sensitive information at risk. Information security has become critically important for organizations and private citizens alike. Hackers scan for network vulnerabilities on the Internet and steal data whenever they can. Cybercrimes disrupt our daily life, cause financial losses, and instigate fear in the public. Since the start of the pandemic, most data related cybercrimes targets have been either financial or health information from companies and organizations. Libraries also should have a high interest in understanding and adopting information security methods to protect their patron data and copyrighted materials. But according to information security professionals, higher education and cultural organizations, including their libraries, are the least prepared entities for cyberattacks. One recent example is that of Steven’s Institute of Technology in New Jersey in the US, which had its network hacked in 2020, with the hackers demanding a ransom. As a result, the network of the college was down for two months, causing serious financial loss. There are other cases where libraries, colleges, and universities have been targeted for data breaches. In order to build an effective defense, we need to understand the most common types of cybercrimes, including phishing, whaling, social engineering, distributed denial of service (DDoS) attacks, malware and ransomware, and hacker profiles. Our research will focus on each hacking technique and related defense measures; and the social background and reasons/purpose of hacker and hacking. Our research shows that hacking techniques will continue to evolve as new applications, housing information, and data on the Internet continue to be developed. Some cybercrimes can be stopped with effective measures, while others present challenges. It is vital that people understand what they face and the consequences when not prepared.

Keywords: cybercrimes, hacking technologies, higher education, information security, libraries

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963 Research on the Optimization of the Facility Layout of Efficient Cafeterias for Troops

Authors: Qing Zhang, Jiachen Nie, Yujia Wen, Guanyuan Kou, Peng Yu, Kun Xia, Qin Yang, Li Ding

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BACKGROUND: A facility layout problem (FLP) is an NP-complete (non-deterministic polynomial) problem, which is hard to obtain an exact optimal solution. FLP has been widely studied in various limited spaces and workflows. For example, cafeterias with many types of equipment for troops cause chaotic processes when dining. OBJECTIVE: This article tried to optimize the layout of troops’ cafeteria and to improve the overall efficiency of the dining process. METHODS: First, the original cafeteria layout design scheme was analyzed from an ergonomic perspective and two new design schemes were generated. Next, three facility layout models were designed, and further simulation was applied to compare the total time and density of troops between each scheme. Last, an experiment of the dining process with video observation and analysis verified the simulation results. RESULTS: In a simulation, the dining time under the second new layout is shortened by 2.25% and 1.89% (p<0.0001, p=0.0001) compared with the other two layouts, while troops-flow density and interference both greatly reduced in the two new layouts. In the experiment, process completing time and the number of interference reduced as well, which verified corresponding simulation results. CONCLUSIONS: Our two new layout schemes are tested to be optimal by a series of simulation and space experiments. In future research, similar approaches could be applied when taking layout-design algorithm calculation into consideration.

Keywords: layout optimization, dining efficiency, troops’ cafeteria, anylogic simulation, field experiment

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962 Design Recommendation for H-shapes Steel Beam with Unreinforced Circular Web Opening

Authors: Facundo L. Vasconsellos, Erwin

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In building construction, the use of web opening as a passage for service pipes is very common with the main purpose of space saving. The strength of the beam may be reduced by this opening, and thus, the configuration of the web opening should be well-designed. A design guide to aid the design of the beam with web opening is available, but it was established based on studies on the beam subjected to gravity-type loading. In simple words, there are no clear design guidelines for the design of beams with web openings subjected to seismic-type loading, which is required in Taiwan. Without any clear guidelines, engineers tend to design the web opening based on their experience, and in most cases, the design is too conservative. A massive amount of reinforcement is sometimes required even though the opening is introduced to the web in low-stress regions. The cost of the reinforcement is usually high. In view of the current situation, there exists a need to investigate the seismic behavior of beams subjected to seismic-type loading so that practical solutions can be provided to aid the engineer in designing the beams with web openings. The current study focuses on investigating the seismic behavior of beams with unreinforced web openings subjected to seismic-type loading. As the preliminary study, the scope of the study is limited to the beam that is only subjected to uniformly distributed gravity load before being subjected to seismic-type loading. The main objective of this study is to confirm that there exists a chance for introducing a web opening without any reinforcement on a beam subjected to seismic-type loading. Three beams, one without and two with circular web openings, were tested to observe how web openings will affect the beam performance under seismic load. The test result shows that for the beam section and length tested in this study, the presence of the web opening located relatively close to the beam plastic hinge region did not affect the overall performance of the beam. No distinct difference in hysteretic behavior can be observed between the beams with and without web opening. The chance of introducing unreinforced web openings on beams designed as highly ductile members exists. Following the test, numerical simulation was also conducted to investigate the hysteretic behavior of various dimensions of beams with one large unreinforced circular web opening. As a result, a design recommendation is proposed to aid the engineer in judging whether the opening reinforcement is required or not. Without reinforcement, considerable cost savings can be achieved.

Keywords: circular web opening, seismic design, steel beam design, unreinforced web opening

Procedia PDF Downloads 22
961 Modeling Stream Flow with Prediction Uncertainty by Using SWAT Hydrologic and RBNN Neural Network Models for Agricultural Watershed in India

Authors: Ajai Singh

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Simulation of hydrological processes at the watershed outlet through modelling approach is essential for proper planning and implementation of appropriate soil conservation measures in Damodar Barakar catchment, Hazaribagh, India where soil erosion is a dominant problem. This study quantifies the parametric uncertainty involved in simulation of stream flow using Soil and Water Assessment Tool (SWAT), a watershed scale model and Radial Basis Neural Network (RBNN), an artificial neural network model. Both the models were calibrated and validated based on measured stream flow and quantification of the uncertainty in SWAT model output was assessed using ‘‘Sequential Uncertainty Fitting Algorithm’’ (SUFI-2). Though both the model predicted satisfactorily, but RBNN model performed better than SWAT with R2 and NSE values of 0.92 and 0.92 during training, and 0.71 and 0.70 during validation period, respectively. Comparison of the results of the two models also indicates a wider prediction interval for the results of the SWAT model. The values of P-factor related to each model shows that the percentage of observed stream flow values bracketed by the 95PPU in the RBNN model as 91% is higher than the P-factor in SWAT as 87%. In other words the RBNN model estimates the stream flow values more accurately and with less uncertainty. It could be stated that RBNN model based on simple input could be used for estimation of monthly stream flow, missing data, and testing the accuracy and performance of other models.

Keywords: SWAT, RBNN, SUFI 2, bootstrap technique, stream flow, simulation

Procedia PDF Downloads 328
960 PathoPy2.0: Application of Fractal Geometry for Early Detection and Histopathological Analysis of Lung Cancer

Authors: Rhea Kapoor

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Fractal dimension provides a way to characterize non-geometric shapes like those found in nature. The purpose of this research is to estimate Minkowski fractal dimension of human lung images for early detection of lung cancer. Lung cancer is the leading cause of death among all types of cancer and an early histopathological analysis will help reduce deaths primarily due to late diagnosis. A Python application program, PathoPy2.0, was developed for analyzing medical images in pixelated format and estimating Minkowski fractal dimension using a new box-counting algorithm that allows windowing of images for more accurate calculation in the suspected areas of cancerous growth. Benchmark geometric fractals were used to validate the accuracy of the program and changes in fractal dimension of lung images to indicate the presence of issues in the lung. The accuracy of the program for the benchmark examples was between 93-99% of known values of the fractal dimensions. Fractal dimension values were then calculated for lung images, from National Cancer Institute, taken over time to correctly detect the presence of cancerous growth. For example, as the fractal dimension for a given lung increased from 1.19 to 1.27 due to cancerous growth, it represents a significant change in fractal dimension which lies between 1 and 2 for 2-D images. Based on the results obtained on many lung test cases, it was concluded that fractal dimension of human lungs can be used to diagnose lung cancer early. The ideas behind PathoPy2.0 can also be applied to study patterns in the electrical activity of the human brain and DNA matching.

Keywords: fractals, histopathological analysis, image processing, lung cancer, Minkowski dimension

Procedia PDF Downloads 140
959 Distribution and Population Status of Canis spp. Threats and Conservation in Lehri Nature Park, Salt Range, District Jhelum

Authors: Muhammad Saad, AzherBaig, Anwar Maqsood, Muhammad Waseem

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The grey wolf has been ranked endangered and Asiatic jackal as near threatened in Pakistan. Scientific data on population and threats to these species are not available in Pakistan, which is required for their proper management and conservation. The present study was conducted to collect data on distribution range, population status and threats to both of these Canis species in Lehri Nature Park. The data were collected using direct observations and indirect signs in the field. The population of grey wolf and Asiatic jackal were scattered into pocket of the study area and its surroundings. The current population of grey wolf was estimated 06 individuals and that of Asiatic jackal 28 individuals in the study area. The present study showed that grey wolf and Asiatic jackal were distributed in the northern and southern part of the study area having dense vegetation cover of tress and shrub between the altitudes of 330 m and 515 m. The research finding revealed that the scrub forest is the most preferred habitat of both the species but due to anthropogenic pressure the scrub forest is under severe threat. The dominant trees species were Acacia modesta, Zizyphus nummularia, and Prosopis juliflora and shrubs species of Dodonea-viscosa, Calotropis procera and Adhatoda vasica. Urial is one of the natural prey species: their population is low due to a number of reasons and therefore the maximum dependence of the wolves was on the livestock of the local and nomadic shepherds. The main prey species in the livestock was goats and sheep. The interviews were conducted with the eye witnesses of wolf attacks including livestock being killed by 5-6 numbers of wolves in different hamlets in the study area. The killing rate of the livestock by the wolves was greater when the nomadic shepherds were present in the area and decreased when they left the area. Presence of nomadic shepherds and killing rate has relation with the shifting of the wolves from the study area. It is further concluded that the population of the grey wolf and Asiatic jackal has decreased over time due to less availability of the natural prey species and habitat destruction.

Keywords: wildlife ecology, population conservation, rehabilitation, conservation

Procedia PDF Downloads 473
958 Multimodal Database of Retina Images for Africa: The First Open Access Digital Repository for Retina Images in Sub Saharan Africa

Authors: Simon Arunga, Teddy Kwaga, Rita Kageni, Michael Gichangi, Nyawira Mwangi, Fred Kagwa, Rogers Mwavu, Amos Baryashaba, Luis F. Nakayama, Katharine Morley, Michael Morley, Leo A. Celi, Jessica Haberer, Celestino Obua

Abstract:

Purpose: The main aim for creating the Multimodal Database of Retinal Images for Africa (MoDRIA) was to provide a publicly available repository of retinal images for responsible researchers to conduct algorithm development in a bid to curb the challenges of ophthalmic artificial intelligence (AI) in Africa. Methods: Data and retina images were ethically sourced from sites in Uganda and Kenya. Data on medical history, visual acuity, ocular examination, blood pressure, and blood sugar were collected. Retina images were captured using fundus cameras (Foru3-nethra and Canon CR-Mark-1). Images were stored on a secure online database. Results: The database consists of 7,859 retinal images in portable network graphics format from 1,988 participants. Images from patients with human immunodeficiency virus were 18.9%, 18.2% of images were from hypertensive patients, 12.8% from diabetic patients, and the rest from normal’ participants. Conclusion: Publicly available data repositories are a valuable asset in the development of AI technology. Therefore, is a need for the expansion of MoDRIA so as to provide larger datasets that are more representative of Sub-Saharan data.

Keywords: retina images, MoDRIA, image repository, African database

Procedia PDF Downloads 83
957 A POX Controller Module to Collect Web Traffic Statistics in SDN Environment

Authors: Wisam H. Muragaa, Kamaruzzaman Seman, Mohd Fadzli Marhusin

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Software Defined Networking (SDN) is a new norm of networks. It is designed to facilitate the way of managing, measuring, debugging and controlling the network dynamically, and to make it suitable for the modern applications. Generally, measurement methods can be divided into two categories: Active and passive methods. Active measurement method is employed to inject test packets into the network in order to monitor their behaviour (ping tool as an example). Meanwhile the passive measurement method is used to monitor the traffic for the purpose of deriving measurement values. The measurement methods, both active and passive, are useful for the collection of traffic statistics, and monitoring of the network traffic. Although there has been a work focusing on measuring traffic statistics in SDN environment, it was only meant for measuring packets and bytes rates for non-web traffic. In this study, a feasible method will be designed to measure the number of packets and bytes in a certain time, and facilitate obtaining statistics for both web traffic and non-web traffic. Web traffic refers to HTTP requests that use application layer; while non-web traffic refers to ICMP and TCP requests. Thus, this work is going to be more comprehensive than previous works. With a developed module on POX OpenFlow controller, information will be collected from each active flow in the OpenFlow switch, and presented on Command Line Interface (CLI) and wireshark interface. Obviously, statistics that will be displayed on CLI and on wireshark interfaces include type of protocol, number of bytes and number of packets, among others. Besides, this module will show the number of flows added to the switch whenever traffic is generated from and to hosts in the same statistics list. In order to carry out this work effectively, our Python module will send a statistics request message to the switch requesting its current ports and flows statistics in every five seconds; while the switch will reply with the required information in a message called statistics reply message. Thus, POX controller will be notified and updated with any changes could happen in the entire network in a very short time. Therefore, our aim of this study is to prepare a list for the important statistics elements that are collected from the whole network, to be used for any further researches; particularly, those that are dealing with the detection of the network attacks that cause a sudden rise in the number of packets and bytes like Distributed Denial of Service (DDoS).

Keywords: mininet, OpenFlow, POX controller, SDN

Procedia PDF Downloads 196
956 Estimating CO₂ Storage Capacity under Geological Uncertainty Using 3D Geological Modeling of Unconventional Reservoir Rocks in Block nv32, Shenvsi Oilfield, China

Authors: Ayman Mutahar Alrassas, Shaoran Ren, Renyuan Ren, Hung Vo Thanh, Mohammed Hail Hakimi, Zhenliang Guan

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The significant effect of CO₂ on global climate and the environment has gained more concern worldwide. Enhance oil recovery (EOR) associated with sequestration of CO₂ particularly into the depleted oil reservoir is considered the viable approach under financial limitations since it improves the oil recovery from the existing oil reservoir and boosts the relation between global-scale of CO₂ capture and geological sequestration. Consequently, practical measurements are required to attain large-scale CO₂ emission reduction. This paper presents an integrated modeling workflow to construct an accurate 3D reservoir geological model to estimate the storage capacity of CO₂ under geological uncertainty in an unconventional oil reservoir of the Paleogene Shahejie Formation (Es1) in the block Nv32, Shenvsi oilfield, China. In this regard, geophysical data, including well logs of twenty-two well locations and seismic data, were combined with geological and engineering data and used to construct a 3D reservoir geological modeling. The geological modeling focused on four tight reservoir units of the Shahejie Formation (Es1-x1, Es1-x2, Es1-x3, and Es1-x4). The validated 3D reservoir models were subsequently used to calculate the theoretical CO₂ storage capacity in the block Nv32, Shenvsi oilfield. Well logs were utilized to predict petrophysical properties such as porosity and permeability, and lithofacies and indicate that the Es1 reservoir units are mainly sandstone, shale, and limestone with a proportion of 38.09%, 32.42%, and 29.49, respectively. Well log-based petrophysical results also show that the Es1 reservoir units generally exhibit 2–36% porosity, 0.017 mD to 974.8 mD permeability, and moderate to good net to gross ratios. These estimated values of porosity, permeability, lithofacies, and net to gross were up-scaled and distributed laterally using Sequential Gaussian Simulation (SGS) and Simulation Sequential Indicator (SIS) methods to generate 3D reservoir geological models. The reservoir geological models show there are lateral heterogeneities of the reservoir properties and lithofacies, and the best reservoir rocks exist in the Es1-x4, Es1-x3, and Es1-x2 units, respectively. In addition, the reservoir volumetric of the Es1 units in block Nv32 was also estimated based on the petrophysical property models and fund to be between 0.554368

Keywords: CO₂ storage capacity, 3D geological model, geological uncertainty, unconventional oil reservoir, block Nv32

Procedia PDF Downloads 145
955 Research on Detection of Web Page Visual Salience Region Based on Eye Tracker and Spectral Residual Model

Authors: Xiaoying Guo, Xiangyun Wang, Chunhua Jia

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Web page has been one of the most important way of knowing the world. Humans catch a lot of information from it everyday. Thus, understanding where human looks when they surfing the web pages is rather important. In normal scenes, the down-top features and top-down tasks significantly affect humans’ eye movement. In this paper, we investigated if the conventional visual salience algorithm can properly predict humans’ visual attractive region when they viewing the web pages. First, we obtained the eye movement data when the participants viewing the web pages using an eye tracker. By the analysis of eye movement data, we studied the influence of visual saliency and thinking way on eye-movement pattern. The analysis result showed that thinking way affect human’ eye-movement pattern much more than visual saliency. Second, we compared the results of web page visual salience region extracted by Itti model and Spectral Residual (SR) model. The results showed that Spectral Residual (SR) model performs superior than Itti model by comparison with the heat map from eye movements. Considering the influence of mind habit on humans’ visual region of interest, we introduced one of the most important cue in mind habit-fixation position to improved the SR model. The result showed that the improved SR model can better predict the human visual region of interest in web pages.

Keywords: web page salience region, eye-tracker, spectral residual, visual salience

Procedia PDF Downloads 247
954 Improved Classification Procedure for Imbalanced and Overlapped Situations

Authors: Hankyu Lee, Seoung Bum Kim

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The issue with imbalance and overlapping in the class distribution becomes important in various applications of data mining. The imbalanced dataset is a special case in classification problems in which the number of observations of one class (i.e., major class) heavily exceeds the number of observations of the other class (i.e., minor class). Overlapped dataset is the case where many observations are shared together between the two classes. Imbalanced and overlapped data can be frequently found in many real examples including fraud and abuse patients in healthcare, quality prediction in manufacturing, text classification, oil spill detection, remote sensing, and so on. The class imbalance and overlap problem is the challenging issue because this situation degrades the performance of most of the standard classification algorithms. In this study, we propose a classification procedure that can effectively handle imbalanced and overlapped datasets by splitting data space into three parts: nonoverlapping, light overlapping, and severe overlapping and applying the classification algorithm in each part. These three parts were determined based on the Hausdorff distance and the margin of the modified support vector machine. An experiments study was conducted to examine the properties of the proposed method and compared it with other classification algorithms. The results showed that the proposed method outperformed the competitors under various imbalanced and overlapped situations. Moreover, the applicability of the proposed method was demonstrated through the experiment with real data.

Keywords: classification, imbalanced data with class overlap, split data space, support vector machine

Procedia PDF Downloads 276
953 Patent on Brian: Brain Waves Stimulation

Authors: Jalil Qoulizadeh, Hasan Sadeghi

Abstract:

Brain waves are electrical wave patterns that are produced in the human brain. Knowing these waves and activating them can have a positive effect on brain function and ultimately create an ideal life. The brain has the ability to produce waves from 0.1 to above 65 Hz. (The Beta One device produces exactly these waves) This is because it is said that the waves produced by the Beta One device exactly match the waves produced by the brain. The function and method of this device is based on the magnetic stimulation of the brain. The technology used in the design and producƟon of this device works in a way to strengthen and improve the frequencies of brain waves with a pre-defined algorithm according to the type of requested function, so that the person can access the expected functions in life activities. to perform better. The effect of this field on neurons and their stimulation: In order to evaluate the effect of this field created by the device, on the neurons, the main tests are by conducting electroencephalography before and after stimulation and comparing these two baselines by qEEG or quantitative electroencephalography method using paired t-test in 39 subjects. It confirms the significant effect of this field on the change of electrical activity recorded after 30 minutes of stimulation in all subjects. The Beta One device is able to induce the appropriate pattern of the expected functions in a soft and effective way to the brain in a healthy and effective way (exactly in accordance with the harmony of brain waves), the process of brain activities first to a normal state and then to a powerful one. Production of inexpensive neuroscience equipment (compared to existing rTMS equipment) Magnetic brain stimulation for clinics - homes - factories and companies - professional sports clubs.

Keywords: stimulation, brain, waves, betaOne

Procedia PDF Downloads 54
952 Getting Out of the Box: Tangible Music Production in the Age of Virtual Technological Abundance

Authors: Tim Nikolsky

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This paper seeks to explore the different ways in which music producers choose to embrace various levels of technology based on musical values, objectives, affordability, access and workflow benefits. Current digital audio production workflow is questioned. Engineers and music producers of today are increasingly divorced from the tangibility of music production. Making music no longer requires you to reach over and turn a knob. Ideas of authenticity in music production are being redefined. Calculations from the mathematical algorithm with the pretty pictures are increasingly being chosen over hardware containing transformers and tubes. Are mouse clicks and movements equivalent or inferior to the master brush strokes we are seeking to conjure? We are making audio production decisions visually by constantly looking at a screen rather than listening. Have we compromised our music objectives and values by removing the ‘hands-on’ nature of music making? DAW interfaces are making our musical decisions for us not necessarily in our best interests. Technological innovation has presented opportunities as well as challenges for education. What do music production students actually need to learn in a formalised education environment, and to what extent do they need to know it? In this brave new world of omnipresent music creation tools, do we still need tangibility in music production? Interviews with prominent Australian music producers that work in a variety of fields will be featured in this paper, and will provide insight in answering these questions and move towards developing an understanding how tangibility can be rediscovered in the next generation of music production.

Keywords: analogue, digital, digital audio workstation, music production, plugins, tangibility, technology, workflow

Procedia PDF Downloads 245
951 Increasing of Gain in Unstable Thin Disk Resonator

Authors: M. Asl. Dehghan, M. H. Daemi, S. Radmard, S. H. Nabavi

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Thin disk lasers are engineered for efficient thermal cooling and exhibit superior performance for this task. However the disk thickness and large pumped area make the use of this gain format in a resonator difficult when constructing a single-mode laser. Choosing an unstable resonator design is beneficial for this purpose. On the other hand, the low gain medium restricts the application of unstable resonators to low magnifications and therefore to a poor beam quality. A promising idea to enable the application of unstable resonators to wide aperture, low gain lasers is to couple a fraction of the out coupled radiation back into the resonator. The output coupling gets dependent on the ratio of the back reflection and can be adjusted independently from the magnification. The excitation of the converging wave can be done by the use of an external reflector. The resonator performance is numerically predicted. First of all the threshold condition of linear, V and 2V shape resonator is investigated. Results show that the maximum magnification is 1.066 that is very low for high quality purposes. Inserting an additional reflector covers the low gain. The reflectivity and the related magnification of a 350 micron Yb:YAG disk are calculated. The theoretical model was based on the coupled Kirchhoff integrals and solved numerically by the Fox and Li algorithm. Results show that with back reflection mechanism in combination with increasing the number of beam incidents on disk, high gain and high magnification can occur.

Keywords: unstable resonators, thin disk lasers, gain, external reflector

Procedia PDF Downloads 385