Search results for: small bar
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 4805

Search results for: small bar

3875 Row Detection and Graph-Based Localization in Tree Nurseries Using a 3D LiDAR

Authors: Ionut Vintu, Stefan Laible, Ruth Schulz

Abstract:

Agricultural robotics has been developing steadily over recent years, with the goal of reducing and even eliminating pesticides used in crops and to increase productivity by taking over human labor. The majority of crops are arranged in rows. The first step towards autonomous robots, capable of driving in fields and performing crop-handling tasks, is for robots to robustly detect the rows of plants. Recent work done towards autonomous driving between plant rows offers big robotic platforms equipped with various expensive sensors as a solution to this problem. These platforms need to be driven over the rows of plants. This approach lacks flexibility and scalability when it comes to the height of plants or distance between rows. This paper proposes instead an algorithm that makes use of cheaper sensors and has a higher variability. The main application is in tree nurseries. Here, plant height can range from a few centimeters to a few meters. Moreover, trees are often removed, leading to gaps within the plant rows. The core idea is to combine row detection algorithms with graph-based localization methods as they are used in SLAM. Nodes in the graph represent the estimated pose of the robot, and the edges embed constraints between these poses or between the robot and certain landmarks. This setup aims to improve individual plant detection and deal with exception handling, like row gaps, which are falsely detected as an end of rows. Four methods were developed for detecting row structures in the fields, all using a point cloud acquired with a 3D LiDAR as an input. Comparing the field coverage and number of damaged plants, the method that uses a local map around the robot proved to perform the best, with 68% covered rows and 25% damaged plants. This method is further used and combined with a graph-based localization algorithm, which uses the local map features to estimate the robot’s position inside the greater field. Testing the upgraded algorithm in a variety of simulated fields shows that the additional information obtained from localization provides a boost in performance over methods that rely purely on perception to navigate. The final algorithm achieved a row coverage of 80% and an accuracy of 27% damaged plants. Future work would focus on achieving a perfect score of 100% covered rows and 0% damaged plants. The main challenges that the algorithm needs to overcome are fields where the height of the plants is too small for the plants to be detected and fields where it is hard to distinguish between individual plants when they are overlapping. The method was also tested on a real robot in a small field with artificial plants. The tests were performed using a small robot platform equipped with wheel encoders, an IMU and an FX10 3D LiDAR. Over ten runs, the system achieved 100% coverage and 0% damaged plants. The framework built within the scope of this work can be further used to integrate data from additional sensors, with the goal of achieving even better results.

Keywords: 3D LiDAR, agricultural robots, graph-based localization, row detection

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3874 Sensitivity Improvement of Optical Ring Resonator for Strain Analysis with the Direction of Strain Recognition Possibility

Authors: Tayebeh Sahraeibelverdi, Ahmad Shirazi Hadi Veladi, Mazdak Radmalekshah

Abstract:

Optical sensors became attractive due to preciseness, low power consumption, and intrinsic electromagnetic interference-free characteristic. Among the waveguide optical sensors, cavity-based ones attended for the high Q-factor. Micro ring resonators as a potential platform have been investigated for various applications as biosensors to pressure sensors thanks to their sensitive ring structure responding to any small change in the refractive index. Furthermore, these small micron size structures can come in an array, bringing the opportunity to have any of the resonance in a specific wavelength and be addressed in this way. Another exciting application is applying a strain to the ring and making them an optical strain gauge where the traditional ones are based on the piezoelectric material. Making them in arrays needs electrical wiring and about fifty times bigger in size. Any physical element that impacts the waveguide cross-section, Waveguide elastic-optic property change, or ring circumference can play a role. In comparison, ring size change has a larger effect than others. Here an engineered ring structure is investigated to study the strain effect on the ring resonance wavelength shift and its potential for more sensitive strain devices. At the same time, these devices can measure any strain by mounting on the surface of interest. The idea is to change the" O" shape ring to a "C" shape ring with a small opening starting from 2π/360 or one degree. We used the Mode solution of Lumbrical software to investigate the effect of changing the ring's opening and the shift induced by applied strain. The designed ring radius is a three Micron silicon on isolator ring which can be fabricated by standard complementary metal-oxide-semiconductor (CMOS) micromachining. The measured wavelength shifts from1-degree opening of the ring to a 6-degree opening have been investigated. Opening the ring for 1-degree affects the ring's quality factor from 3000 to 300, showing an order of magnitude Q-factor reduction. Assuming a strain making the ring-opening from 1 degree to 6 degrees, our simulation results showing negligible Q-factor reduction from 300 to 280. A ring resonator quality factor can reach up to 108 where an order of magnitude reduction is negligible. The resonance wavelength shift showed a blue shift and was obtained to be 1581, 1579,1578,1575nm for 1-, 2-, 4- and 6-degree ring-opening, respectively. This design can find the direction of the strain-induced by applying the opening on different parts of the ring. Moreover, by addressing the specified wavelength, we can precisely find the direction. We can open a significant opportunity to find cracks and any surface mechanical property very specifically and precisely. This idea can be implemented on polymer ring resonators while they can come with a flexible substrate and can be very sensitive to any strain making the two ends of the ring in the slit part come closer or further.

Keywords: optical ring resonator, strain gauge, strain sensor, surface mechanical property analysis

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3873 Use of Serum Creatinine as an Incentive to Increase Prep Uptake Among Key Population Groups in South-South Nigeria

Authors: Akhigbe Mark, Abang Roger, Mwoltu Nanaribet, Edet Blessing

Abstract:

Introduction.: The introduction of pre- exposure prophylaxis (PrEP) as a biomedical prevention method for HIV/AIDS has been around for more than a decade since the first confirmed evidence of its effectiveness when used daily as an oral pill. It is now a very valuable addition for people who are at higher risk of contracting HIV. Although globalacceptanceof PrEP hasincreased, PrEP is still highly concentrated in a small number of countries and within a small sub-population, with Kenya and South Africa accounting for only 19% of people who have received PrEP in Africa region, there is still a significant regionGap in PrEP availability and use, with only 28% of the target of 3 million in low-and middle countries currently using PrEP. Description: The purpose of this study is to find out if serum creatinine could be used as an incentive to improve PrEP uptake among Key population.Numerous approaches to increasing the uptake ofPrEP as a prevention mechanism for HIV in KPs has beenemployed, and one of them is serum creatinine. This approach is a biomarker of renal function, which was used in study as an incentive to increase PrEP uptake among key population groups (female sex workers, men who have sex with men, persons who inject drugs, transgender) in 3 states from South-South Nigeria. Whole blood samples are collected from clients, analysis of the samples is done using the clinical chemistry analyzer before they are initiated onto PrEP. Lessons learned and Recommendations: Secondary data was extracted from 3 states of HALG Implementing facilities in Southern part of Nigeria, PrEP uptake before and afterthe introduction of serum creatinine between March 2020 and August 2020 among key populationsin Nigeria. A total of 5664 patients were initiated on PrEP before, and after the introduction of serum creatinine, the PrEP uptake rate before (March 2020 to May 2020) introduction of serum creatinine accounted for only 5% of the total onset, and after (June 2020 to August 2020) introduction of serum creatinine, the uptake rate accounted for 95% of the total onset. These finding shows that increased uptake of PrEP before/after serum creatineindicates that serum creatine may be an effective stimulus for promoting PrEP in key populations.

Keywords: serum creatinine, incentives, PrEP, key populations, Nigeria

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3872 A Review on Investigating the Relations between Water Harvesting and Water Conflicts

Authors: B. Laurita

Abstract:

The importance of Water Harvesting (WH) as an effective mean to deal with water scarcity is universally recognized. The collection and storage of rainwater, floodwater or quick runoff and their conversion to productive uses can ensure water availability for domestic and agricultural use, enabling a lower exploitation of the aquifer, preventing erosion events and providing significant ecosystem services. At the same time, it has been proven that it can reduce the insurgence of water conflicts if supported by a cooperative process of planning and management. On the other hand, the construction of water harvesting structures changes the hydrological regime, affecting upstream-downstream dynamics and changing water allocation, often causing contentions. Furthermore, dynamics existing between water harvesting and water conflict are not properly investigated yet. Thus, objective of this study is to analyze the relations between water harvesting and the insurgence of water conflicts, providing a solid theoretical basis and foundations for future studies. Two search engines were selected in order to perform the study: Google Scholar and Scopus. Separate researches were conducted on the mutual influences between water conflicts and the four main water harvesting techniques: rooftop harvesting, surface harvesting, underground harvesting, runoff harvesting. Some of the aforementioned water harvesting techniques have been developed and implemented on scales ranging from the small, household-sided ones, to gargantuan dam systems. Instead of focusing on the collisions related to large-scale systems, this review is aimed to look for and collect examples of the effects that the implementation of small water harvesting systems has had on the access to the water resource and on water governance. The present research allowed to highlight that in the studies that have been conducted up to now, water harvesting, and in particular those structures that allow the collection and storage of water for domestic use, is usually recognized as a positive, palliative element during contentions. On the other hand, water harvesting can worsen and, in some cases, even generate conflicts for water management. This shows the necessity of studies that consider both benefits and negative influences of water harvesting, analyzing its role respectively as triggering or as mitigating factor of conflicting situations.

Keywords: arid areas, governance, water conflicts, water harvesting

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3871 Political Antinomy and Its Resolution in Islam

Authors: Abdul Nasir Zamir

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After the downfall of Ottoman Caliphate, it scattered into different small Muslim states. Muslim leaders, intellectuals, revivalists as well as modernists started trying to boost up their nation. Some Muslims are also trying to establish the caliphate. Every Muslim country has its own political system, i.e., kingship, dictatorship or democracy, etc. But these are not in their original forms as the historian or political science discussed in their studies. The laws and their practice are mixed, i.e., others with Islamic laws, e.g., Saudi Arabia (K.S.A) and the Islamic Republic of Pakistan, etc. There is great conflict among the revivalist Muslim parties (groups) and governments about political systems. The question is that the subject matter is Sharia or political system? Leaders of Modern Muslim states are alleged as disbelievers due to neglecting the revelation in their laws and decisions. There are two types of laws; Islamic laws and management laws. The conflict is that the non-Islamic laws are in practice in Muslim states. Non-Islamic laws can be gradually changed with Islamic laws with a legal and peaceful process according to the practice of former Muslim leaders and scholars. The bloodshed of Muslims is not allowed in any case. Weak Muslim state is a blessing than nothing. The political system after Muhammad and guided caliphs is considered as kingship. But during this period Muslims not only developed in science and technology but conquered many territories also. If the original aim is in practice, then the Modern Muslim states can be stabled with different political systems. Modern Muslim states are the hope of survival, stability, and development of Muslim Ummah. Islam does not allow arm clash with Muslim army or Muslim civilians. The caliphate is based on believing in one Allah Almighty and good deeds according to Quran and Sunnah. As faith became weak and good deeds became less from its standard level, caliphate automatically became weak and even ended. The last weak caliphate was Ottoman Caliphate which was a hope of all the Muslims of the world. There is no caliphate or caliph present in the world. But every Muslim country or state is like an Amarat (a part of caliphate or small and alternate form of the caliphate) of Muslims. It is the duty of all Muslims to stable these modern Muslim states with tolerance.

Keywords: caliphate, conflict resolution, modern Muslim state, political conflicts, political systems, tolerance

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3870 Multi-Objective Optimization of Run-of-River Small-Hydropower Plants Considering Both Investment Cost and Annual Energy Generation

Authors: Amèdédjihundé H. J. Hounnou, Frédéric Dubas, François-Xavier Fifatin, Didier Chamagne, Antoine Vianou

Abstract:

This paper presents the techno-economic evaluation of run-of-river small-hydropower plants. In this regard, a multi-objective optimization procedure is proposed for the optimal sizing of the hydropower plants, and NSGAII is employed as the optimization algorithm. Annual generated energy and investment cost are considered as the objective functions, and number of generator units (n) and nominal turbine flow rate (QT) constitute the decision variables. Site of Yeripao in Benin is considered as the case study. We have categorized the river of this site using its environmental characteristics: gross head, and first quartile, median, third quartile and mean of flow. Effects of each decision variable on the objective functions are analysed. The results gave Pareto Front which represents the trade-offs between annual energy generation and the investment cost of hydropower plants, as well as the recommended optimal solutions. We noted that with the increase of the annual energy generation, the investment cost rises. Thus, maximizing energy generation is contradictory with minimizing the investment cost. Moreover, we have noted that the solutions of Pareto Front are grouped according to the number of generator units (n). The results also illustrate that the costs per kWh are grouped according to the n and rise with the increase of the nominal turbine flow rate. The lowest investment costs per kWh are obtained for n equal to one and are between 0.065 and 0.180 €/kWh. Following the values of n (equal to 1, 2, 3 or 4), the investment cost and investment cost per kWh increase almost linearly with increasing the nominal turbine flowrate while annual generated. Energy increases logarithmically with increasing of the nominal turbine flowrate. This study made for the Yeripao river can be applied to other rivers with their own characteristics.

Keywords: hydropower plant, investment cost, multi-objective optimization, number of generator units

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3869 Implications about the Impact of COVID-19 on Business

Authors: Anwar Kashgari

Abstract:

COVID-19 has severe impacts on business all over the world. The great lockdown of many business owners requires a sage deal with this pandemic. This paper seeks to support business leaders with a standpoint about the COVID-19 situation and provides implications for the (Small and Medium Enterprises) SMEs and companies. The paper reflects the author's view about the impact of COVID-19 on business activities. We discussed the impact of COVID-19 upon three aspects, namely, startups, SMEs, and e-commerce. The KSA is an example of the developing countries about which we present the current situation. Finally, recommendations to policy and decision-makers are given.

Keywords: COVID 19, business networking, globalization

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3868 Microstructure of Virgin and Aged Asphalts by Small-Angle X-Ray Scattering

Authors: Dong Tang, Yongli Zhao

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The study of the microstructure of asphalt is of great importance for the analysis of its macroscopic properties. However, the peculiarities of the chemical composition of the asphalt itself and the limitations of existing direct imaging techniques have caused researchers to face many obstacles in studying the microstructure of asphalt. The advantage of small-angle X-ray scattering (SAXS) is that it allows quantitative determination of the internal structure of opaque materials and is suitable for analyzing the microstructure of materials. Therefore, the SAXS technique was used to study the evolution of microstructures on the nanoscale during asphalt aging. And the reasons for the change in scattering contrast during asphalt aging were also explained with the help of Fourier transform infrared spectroscopy (FTIR). SAXS experimental results show that the SAXS curves of asphalt are similar to the scattering curves of scattering objects with two-level structures. The Porod curve for asphalt shows that there is no obvious interface between the micelles and the surrounding mediums, and there is only a fluctuation of the hot electron density between the two. The Beaucage model fit SAXS patterns shows that the scattering coefficient P of the asphaltene clusters as well as the size of the micelles, gradually increase with the aging of the asphalt. Furthermore, aggregation exists between the micelles of asphalt and becomes more pronounced with increasing aging. During asphalt aging, the electron density difference between the micelles and the surrounding mediums gradually increases, leading to an increase in the scattering contrast of the asphalt. Under long-term aging conditions due to the gradual transition from maltenes to asphaltenes, the electron density difference between the micelles and the surrounding mediums decreases, resulting in a decrease in the scattering contrast of asphalt SAXS. Finally, this paper correlates the macroscopic properties of asphalt with microstructural parameters, and the results show that the high-temperature rutting resistance of asphalt is enhanced and the low-temperature cracking resistance decreases due to the aggregation of micelles and the generation of new micelles. These results are useful for understanding the relationship between changes in microstructure and changes in properties during asphalt aging and provide theoretical guidance for the regeneration of aged asphalt.

Keywords: asphalt, Beaucage model, microstructure, SAXS

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3867 Open Innovation in SMEs: A Multiple Case Study of Collaboration between Start-ups and Craft Enterprises

Authors: Carl-Philipp Valentin Beichert, Marcel Seger

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Digital transformation and climate change require small and medium-sized enterprises (SME) to rethink their way of doing business. Inter-firm collaboration is recognized as helpful means of promoting innovation and competitiveness. In this context, collaborations with start-ups offer valuable opportunities through their innovative products, services, and business models. SMEs, and in particular German craft enterprises, play an important role in the country’s society and economy. Companies in this heterogeneous economic sector have unique characteristics and are limited in their ability to innovate due to their small size and lack of resources. Collaborating with start-ups could help to overcome these shortcomings. To investigate how collaborations emerge and what factors are decisive to successfully drive collaboration, we apply an explorative, qualitative research design. A sample of ten case studies was selected, with the collaboration between a start-up and a craft enterprise forming the unit of analysis. Semi-structured interviews with 20 company representatives allow for a two-sided perspective on the respective collaboration. The interview data is enriched by publicly available data and three expert interviews. As a result, objectives, initiation practices, applied collaboration types, barriers, as well as key success factors could be identified. The results indicate a three-phase collaboration process comprising an initiation, concept, and partner phase (ICP). The ICP framework proposed accordingly highlights the success factors (personal fit, communication, expertise, structure, network) for craft enterprises and start-ups for each collaboration phase. The role of a mediator in the start-up company, with strong expertise in the respective craft sector, is considered an important lever for overcoming barriers such as cultural and communication differences. The ICP framework thus provides promising directions for further research and can help practitioners establish successful collaborations.

Keywords: open innovation, SME, craft businesses, startup collaboration, qualitative research

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3866 Evaluating and Improving Healthcare Staff Knowledge of the [NG179] NICE Guidelines on Elective Surgical Care during the COVID-19 Pandemic: A Quality Improvement Project

Authors: Stavroula Stavropoulou-Tatla, Danyal Awal, Mohammad Ayaz Hossain

Abstract:

The first wave of the COVID-19 pandemic saw several countries issue guidance postponing all non-urgent diagnostic evaluations and operations, leading to an estimated backlog of 28 million cases worldwide and over 4 million in the UK alone. In an attempt to regulate the resumption of elective surgical activity, the National Institute for Health and Care Excellence (NICE) introduced the ‘COVID-19 rapid guideline [NG179]’. This project aimed to increase healthcare staff knowledge of the aforementioned guideline to a targeted score of 100% in the disseminated questionnaire within 3 months at the Royal Free Hospital. A standardized online questionnaire was used to assess the knowledge of surgical and medical staff at baseline and following each 4-week-long Plan-Study-Do-Act (PDSA) cycle. During PDSA1, the A4 visual summary accompanying the guideline was visibly placed in all relevant clinical areas and the full guideline was distributed to the staff in charge together with a short briefing on the salient points. PDSA2 involved brief small-group teaching sessions. A total of 218 responses was collected. Mean percentage scores increased significantly from 51±19% at baseline to 81±16% after PDSA1 (t=10.32, p<0.0001) and further to 93±8% after PDSA2 (t=4.9, p<0.0001), with 54% of participants achieving a perfect score. In conclusion, the targeted distribution of guideline printouts and visual aids, combined with small-group teaching sessions, were simple and effective ways of educating healthcare staff about the new standards of elective surgical care at the time of COVID-19. This could facilitate the safe restoration of surgical activity, which is critical in order to mitigate the far-reaching consequences of surgical delays on an unprecedented scale during a time of great crisis and uncertainty.

Keywords: COVID-19, elective surgery, NICE guidelines, quality improvement

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3865 Thorium-Doped PbS Thin Films for Radiation Damage Studies

Authors: Michael Shandalov, Tzvi Templeman, Michael Schmidt, Itzhak Kelson, Eyal Yahel

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We present a new method to produce a model system for the study of radiation damage in non-radioactive materials. The method is based on homogeneously incorporating 228Th ions in PbS thin films using a small volume chemical bath deposition (CBD) technique. The common way to alloy metals with radioactive elements is by melting pure elements, which requires considerable amounts of radioactive material with its safety consequences such as high sample activity. Controlled doping of the thin films with (very) small amounts (100-200ppm) of radioactive elements such as thorium is expected to provide a unique path for studying radiation damage in materials due to decay processes without the need of sealed enclosure. As a first stage, we developed CBD process for controlled doping of PbS thin films (~100 nm thick) with the stable isotope (t1/2~106 years), 232Th. Next, we developed CBD process for controlled doping of PbS thin films with active 228Th isotope. This was achieved by altering deposition parameters such as temperature, pH, reagent concentrations and time. The 228Th-doped films were characterized using X-ray diffraction, which indicated a single phase material. Film morphology and thickness were determined using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) mapping in the analytical transmission electron microscope (A-TEM), X-ray photoelectron spectroscopy (XPS) depth profiles and autoradiography indicated that the Th ions were homogeneously distributed throughout the films, suggesting Pb substitution by Th ions in the crystal lattice. The properties of the PbS (228Th) film activity were investigated by using alpha-spectroscopy and gamma spectroscopy. The resulting films are applicable for isochronal annealing of resistivity measurements and currently under investigation. This work shows promise as a model system for the analysis of dilute defect systems in semiconductor thin films.

Keywords: thin films, doping, radiation damage, chemical bath deposition

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3864 NanoSat MO Framework: Simulating a Constellation of Satellites with Docker Containers

Authors: César Coelho, Nikolai Wiegand

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The advancement of nanosatellite technology has opened new avenues for cost-effective and faster space missions. The NanoSat MO Framework (NMF) from the European Space Agency (ESA) provides a modular and simpler approach to the development of flight software and operations of small satellites. This paper presents a methodology using the NMF together with Docker for simulating constellations of satellites. By leveraging Docker containers, the software environment of individual satellites can be easily replicated within a simulated constellation. This containerized approach allows for rapid deployment, isolation, and management of satellite instances, facilitating comprehensive testing and development in a controlled setting. By integrating the NMF lightweight simulator in the container, a comprehensive simulation environment was achieved. A significant advantage of using Docker containers is their inherent scalability, enabling the simulation of hundreds or even thousands of satellites with minimal overhead. Docker's lightweight nature ensures efficient resource utilization, allowing for deployment on a single host or across a cluster of hosts. This capability is crucial for large-scale simulations, such as in the case of mega-constellations, where multiple traditional virtual machines would be impractical due to their higher resource demands. This ability for easy horizontal scaling based on the number of simulated satellites provides tremendous flexibility to different mission scenarios. Our results demonstrate that leveraging Docker containers with the NanoSat MO Framework provides a highly efficient and scalable solution for simulating satellite constellations, offering not only significant benefits in terms of resource utilization and operational flexibility but also enabling testing and validation of ground software for constellations. The findings underscore the importance of taking advantage of already existing technologies in computer science to create new solutions for future satellite constellations in space.

Keywords: containerization, docker containers, NanoSat MO framework, satellite constellation simulation, scalability, small satellites

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3863 Opportunities of Clean Development Mechanism through Hydropower in Nepal

Authors: Usha Khatiwada

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Nepal’s overall energy baseline: It has been proposed that hydropower projects for domestic consumption can earn CDM revenue in Nepal if a new methodology is established that takes into account not only consumption in Nepal of grid electricity but also other fuels such as kerosene, diesel, and firewood, used by a vast majority of the population for their lighting and other needs. However, this would mean that we would be trying to combine grid electricity supply and consumers not supplied from the grid into one methodology. Such a sweeping baseline may have a very small chance of success with the CDM Executive Board.

Keywords: environment, clean development mechanism, hydropower, Nepal

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3862 Pancreatic Adenocarcinoma Correctly Diagnosed by EUS but nor CT or MRI

Authors: Yousef Reda

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Pancreatic cancer has an overall dismal prognosis. CT, MRI and Endoscopic Ultrasound are most often used to establish the diagnosis. We present a case of a patient found on abdominal CT and MRI to have an 8 mm cystic lesion within the head of the pancreas which was thought to be a benign intraductal papillary mucinous neoplasm (IPMN). Further evaluation by EUS demonstrated a 1 cm predominantly solid mass that was proven to be an adenocarcinoma by EUS-guided FNA. The patient underwent a Whipple procedure. The final pathology confirmed a 1 cm pT1 N0 pancreatic ductal adenocarcinoma. Case: A 63-year-old male presented with left upper quadrant pain and an abdominal CT demonstrated an 8 mm lesion within the head of the pancreas that was thought to represent a side branch IPMN. An MRI also showed similar findings. Four months later due to ongoing symptoms an EUS was performed to re-evaluate the pancreatic lesion. EUS revealed a predominantly solid hypoechoic, homogeneous mass measuring 12 mm x 9 mm. EUS-guided FNA was performed and was positive for adenocarcinoma. The patient underwent a Whipple procedure that confirmed it to be a ductal adenocarcinoma, pT1N0. The solid mass was noted to be adjacent to a cystic dilation with no papillary architecture and scant epithelium. The differential diagnosis resided between cystic degeneration of a primary pancreatic adenocarcinoma versus malignant degeneration within a side-branch IPMN. Discussion: The reported sensitivity of CT for pancreatic cancer is approximately 90%. For pancreatic tumors, less than 3 cm the sensitivity of CT is reduced ranging from 67-77%. MRI does not significantly improve overall detection rates compared to CT. EUS, however is superior to CT in the detection of pancreatic cancer, in particular among lesions smaller than 3 cm. EUS also outperforms CT and MRI in distinguishing neoplastic from non-neoplastic cysts. In this case, both MRI and CT failed to detect a small pancreatic adenocarcinoma. The addition of EUS and FNA to abdominal imaging can increase overall accuracy for the diagnosis of neoplastic pancreatic lesions. It may be prudent that when small lesions although appearing as a benign IPMN should further be evaluated by EUS as this would lead to potentially identifying earlier stage pancreatic cancers and improve survival in a disease which has a dismal prognosis.

Keywords: IPMN, MRI, EUS, CT

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3861 Discovery of Exoplanets in Kepler Data Using a Graphics Processing Unit Fast Folding Method and a Deep Learning Model

Authors: Kevin Wang, Jian Ge, Yinan Zhao, Kevin Willis

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Kepler has discovered over 4000 exoplanets and candidates. However, current transit planet detection techniques based on the wavelet analysis and the Box Least Squares (BLS) algorithm have limited sensitivity in detecting minor planets with a low signal-to-noise ratio (SNR) and long periods with only 3-4 repeated signals over the mission lifetime of 4 years. This paper presents a novel precise-period transit signal detection methodology based on a new Graphics Processing Unit (GPU) Fast Folding algorithm in conjunction with a Convolutional Neural Network (CNN) to detect low SNR and/or long-period transit planet signals. A comparison with BLS is conducted on both simulated light curves and real data, demonstrating that the new method has higher speed, sensitivity, and reliability. For instance, the new system can detect transits with SNR as low as three while the performance of BLS drops off quickly around SNR of 7. Meanwhile, the GPU Fast Folding method folds light curves 25 times faster than BLS, a significant gain that allows exoplanet detection to occur at unprecedented period precision. This new method has been tested with all known transit signals with 100% confirmation. In addition, this new method has been successfully applied to the Kepler of Interest (KOI) data and identified a few new Earth-sized Ultra-short period (USP) exoplanet candidates and habitable planet candidates. The results highlight the promise for GPU Fast Folding as a replacement to the traditional BLS algorithm for finding small and/or long-period habitable and Earth-sized planet candidates in-transit data taken with Kepler and other space transit missions such as TESS(Transiting Exoplanet Survey Satellite) and PLATO(PLAnetary Transits and Oscillations of stars).

Keywords: algorithms, astronomy data analysis, deep learning, exoplanet detection methods, small planets, habitable planets, transit photometry

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3860 Driving Performance Improvement in Mini Markets: The Impact of Talent Management, Business Skills, and Technology Adoption in Johannesburg and Cape Town, South Africa

Authors: Fedil Jemal Ahmed

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This conference abstract paper presents a study that aimed to explore the impact of talent management and business skills on performance improvement in mini markets located in Johannesburg and Cape Town, South Africa. Mini markets are small retail stores that play a crucial role in providing essential goods and services to communities. However, due to their small size, they often face significant challenges in terms of resources and management. The study conducted interviews with mini market owners and managers in Johannesburg and Cape Town to understand their approach to talent management, business skills, and their impact on business performance. The results showed that effective talent management practices, including recruitment, training, and retention, along with strong business skills, had a significant positive impact on business performance in mini markets. Furthermore, the study found that the use of technology, such as point of sale systems and inventory management software, can also contribute to business performance improvement in mini markets. The results suggest that mini market owners and managers should prioritize talent management, business skills, and invest in technology to improve their business performance. Comparing the improvements made by mini markets in Johannesburg and Cape Town to those made by others, the study found that the adoption of effective talent management practices and strong business skills were key factors in driving performance improvement. Mini market owners and managers who invested in these areas were better equipped to manage their resources, enhance their customer service, and increase their profitability. When comparing the personal experiences of the fedil jemal who improved their business performance from a small market to a large one, they found that effective talent management practices and strong business skills were crucial in achieving success. Through the adoption of effective talent management practices, the fedil was able to attract and retain top talent, ensuring that the business was managed effectively. Furthermore, the fedil invested in improving their business skills, such as financial management, marketing, and customer service, which helped to increase their revenue and profitability. In terms of technology adoption, the author found that the use of point-of-sale systems and inventory management software were essential in managing their inventory and improving their customer service. By investing in technology, the fedil was able to streamline their operations and enhance their overall business performance. In conclusion, this study provides valuable insights into the importance of talent management, business skills, and technology adoption in improving business performance in mini markets. It highlights the need for mini market owners and managers to prioritize these areas and invest in them to enhance their business performance. The findings of this study have practical implications for mini market owners and managers who are looking to improve their business performance and compete in a highly competitive market. By adopting effective talent management practices, developing strong business skills, and investing in technology, mini market owners and managers can improve their operations and increase their profitability.

Keywords: talent management, business skills, technology adoption, mini markets

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3859 The Efficacy of Psychological Interventions for Psychosis: A Systematic Review and Network Meta-Analysis

Authors: Radu Soflau, Lia-Ecaterina Oltean

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Background: Increasing evidence supports the efficacy of psychological interventions for psychosis. However, it is unclear which one of these interventions is most likely to address negative psychotic symptoms and related outcomes. We aimed to determine the relative efficacy of psychological and psychosocial interventions for negative symptoms, overall psychotic symptoms, and related outcomes. Methods: To attain this goal, we conducted a systematic review and network meta-analysis. We searched for potentially eligible trials in PubMed, EMBASE, PsycInfo, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov databases up until February 08, 2022. We included randomized controlled trials that investigated the efficacy of psychological for adults with psychosis. We excluded interventions for prodromal or “at risk” individuals, as well as patients with serious co-morbid medical or psychiatric conditions (others than depressive and/or anxiety disorders). Two researchers conducted study selection and performed data extraction independently. Analyses were run using STATA network and mvmeta packages, applying a random effect model under a frequentist framework in order to compute standardized mean differences or risk ratio. Findings: We identified 47844 records and screened 29466 records for eligibility. The majority of eligible interventions were delivered in addition to pharmacological treatment. Treatment as usual (TAU) was the most frequent common comparator. Theoretically driven psychological interventions generally outperformed TAU at post-test and follow-up, displaying small and small-to-medium effect sizes. A similar pattern of results emerged in sensitivity analyses focused on studies that employed an inclusion criterion for relevant negative symptom severity. Conclusion: While the efficacy of some psychological interventions is promising, there is a need for more high-quality studies, as well as more trials directly comparing psychological treatments for negative psychotic symptoms.

Keywords: psychosis, network meta-analysis, psychological interventions, efficacy, negative symptoms

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3858 Availability and Utilization of Health Care Facilities in Jalpaiguri Town

Authors: Sharmistha Mukherjee

Abstract:

Health care is the basic requirement for all. The prime question is who gets what, where and how? The unequal distribution of basic facilities do have a adverse effect on the users. The paper tries to examine health care in terms of available facilities, the health care need and how people perceive to it in a small town of Jalpaiguri in the midst of tea gardens in North Bengal. The morbidity pattern is also minutely observed with a section describing the organizational structure of health care keeping in mind the utilization.

Keywords: availability, distribution, health care, utilization

Procedia PDF Downloads 524
3857 The Pathology of Bovine Rotavirus Infection in Calves That Confirmed by Enzyme Linked Immunosorbant Assay, Reverse Transcription Polymerase Chain Reaction and Real-Time RT-PCR

Authors: Shama Ranjan Barua, Tofazzal M. Rakib, Mohammad Alamgir Hossain, Tania Ferdushy, Sharmin Chowdhury

Abstract:

Rotavirus is one of the main etiologies of neonatal diarrhea in bovine calves that causes significant economic loss in Bangladesh. The present study was carried out to investigate the pathology of neonatal enteritis in calves due to bovine rotavirus infection in south-eastern part of Bangladesh. Rotavirus was identified by using ELISA, RT-PCR (Reverse Transcription Polymerase Chain Reaction), real-time RT-PCR. We examined 12 dead calves with history of diarrhea during necropsy. Among 12 dead calves, in gross examination, 6 were found with pathological changes in intestine, 5 calves had congestion of small intestine and rest one had no distinct pathological changes. Intestinal contents and/or faecal samples of all dead calves were collected and examined to confirm the presence of bovine rotavirus A using Enzyme linked immunosorbant assay (ELISA), RT-PCR and real-time RT-PCR. Out 12 samples, 5 (42%) samples revealed presence of bovine rotavirus A in three diagnostic tests. The histopathological changes were found almost exclusively limited in the small intestine. The lesions of rotaviral enteritis ranged from slight to moderate shortening (atrophy) of villi in the jejunum and ileum with necrotic crypts. The villi were blunt and covered by immature epithelial cells. Infected cells, stained with Haematoxylin and Eosin staining method, showed characteristic syncytia and eosinophilc intracytoplasmic inclusion body. The presence of intracytoplasmic inclusion bodies in enterocytes is the indication of viral etiology. The presence of rotavirus in the affected tissues and/or lesions was confirmed by three different immunological and molecular tests. The findings of histopathological changes will be helpful in future diagnosis of rotaviral infection in dead calves.

Keywords: calves, diarrhea, pathology, rotavirus

Procedia PDF Downloads 252
3856 Lineup Optimization Model of Basketball Players Based on the Prediction of Recursive Neural Networks

Authors: Wang Yichen, Haruka Yamashita

Abstract:

In recent years, in the field of sports, decision making such as member in the game and strategy of the game based on then analysis of the accumulated sports data are widely attempted. In fact, in the NBA basketball league where the world's highest level players gather, to win the games, teams analyze the data using various statistical techniques. However, it is difficult to analyze the game data for each play such as the ball tracking or motion of the players in the game, because the situation of the game changes rapidly, and the structure of the data should be complicated. Therefore, it is considered that the analysis method for real time game play data is proposed. In this research, we propose an analytical model for "determining the optimal lineup composition" using the real time play data, which is considered to be difficult for all coaches. In this study, because replacing the entire lineup is too complicated, and the actual question for the replacement of players is "whether or not the lineup should be changed", and “whether or not Small Ball lineup is adopted”. Therefore, we propose an analytical model for the optimal player selection problem based on Small Ball lineups. In basketball, we can accumulate scoring data for each play, which indicates a player's contribution to the game, and the scoring data can be considered as a time series data. In order to compare the importance of players in different situations and lineups, we combine RNN (Recurrent Neural Network) model, which can analyze time series data, and NN (Neural Network) model, which can analyze the situation on the field, to build the prediction model of score. This model is capable to identify the current optimal lineup for different situations. In this research, we collected all the data of accumulated data of NBA from 2019-2020. Then we apply the method to the actual basketball play data to verify the reliability of the proposed model.

Keywords: recurrent neural network, players lineup, basketball data, decision making model

Procedia PDF Downloads 134
3855 The Observable Method for the Regularization of Shock-Interface Interactions

Authors: Teng Li, Kamran Mohseni

Abstract:

This paper presents an inviscid regularization technique that is capable of regularizing the shocks and sharp interfaces simultaneously in the shock-interface interaction simulations. The direct numerical simulation of flows involving shocks has been investigated for many years and a lot of numerical methods were developed to capture the shocks. However, most of these methods rely on the numerical dissipation to regularize the shocks. Moreover, in high Reynolds number flows, the nonlinear terms in hyperbolic Partial Differential Equations (PDE) dominates, constantly generating small scale features. This makes direct numerical simulation of shocks even harder. The same difficulty happens in two-phase flow with sharp interfaces where the nonlinear terms in the governing equations keep sharpening the interfaces to discontinuities. The main idea of the proposed technique is to average out the small scales that is below the resolution (observable scale) of the computational grid by filtering the convective velocity in the nonlinear terms in the governing PDE. This technique is named “observable method” and it results in a set of hyperbolic equations called observable equations, namely, observable Navier-Stokes or Euler equations. The observable method has been applied to the flow simulations involving shocks, turbulence, and two-phase flows, and the results are promising. In the current paper, the observable method is examined on the performance of regularizing shocks and interfaces at the same time in shock-interface interaction problems. Bubble-shock interactions and Richtmyer-Meshkov instability are particularly chosen to be studied. Observable Euler equations will be numerically solved with pseudo-spectral discretization in space and third order Total Variation Diminishing (TVD) Runge Kutta method in time. Results are presented and compared with existing publications. The interface acceleration and deformation and shock reflection are particularly examined.

Keywords: compressible flow simulation, inviscid regularization, Richtmyer-Meshkov instability, shock-bubble interactions.

Procedia PDF Downloads 349
3854 Knowledge, Attitude, and Practices of Small Scale Farmers on Organic Agriculture in a Rural Community in Ifugao, Philippines

Authors: Marah Joy A. Nanglegan

Abstract:

A survey was conducted to describe knowledge, attitude, practices, information needs, and information seeking behavior of small-scale farmers on Organic Agriculture Production (OAP) in a rural community in Ifugao, Philippines. Respondents’ age ranged from 23-67 years old. Most of them are male, married, and have reached high school level. The major source of income is farming with an average monthly income of less than Php 5,000 for a household size of seven. More than fifty percent of the respondents are members of a farmer’s organization. Farm size is less than one hectare. Majority of them own their farms and have been farming for more than twenty years. Very few attended training on Organic Agriculture Production (OAP). Most of them are not aware of any OAP program in their community. Hence, their farming practices are mostly conventional. The overall level of knowledge on OAP among all respondents was below the average. On attitude, most of the respondents agreed that organic farming would decrease production costs by reducing input purchases. They believe it benefits both the consumer and the producer. In fact, they are aware of the many benefits of organic farming, especially on health. Likewise, many of them agreed on the benefits of organic farming to soil fertility, to the environment, and to increase the income of farmers. Many of them, however, see organic farming as troublesome and difficult in terms of time and effort, obtaining organic inputs, limited production, and marketing aspects. They also have heavy reliance on pesticides and herbicides to control pests and diseases. On practices, majority of the respondents stated that they practiced crop rotation, manual weeding, and the use of animal manure. Most of them desired to do organic farming but needed information such as production techniques, costs, and marketing opportunities. Their most preferred communication channel is through extension agents and contact farmers. Their most preferred communication method is through trainings and seminars as well as through farm demonstrations. Results of this study will serve as a basis for developing appropriate communication strategies to improve knowledge, attitude, and practices of respondents on organic agriculture as well as enhance the promotion of organic agriculture production in the community.

Keywords: Ifugao, knowledge attitude practices, organic agriculture, Philippines

Procedia PDF Downloads 165
3853 Performance Analysis of Three Absorption Heat Pump Cycles, Full and Partial Loads Operations

Authors: B. Dehghan, T. Toppi, M. Aprile, M. Motta

Abstract:

The environmental concerns related to global warming and ozone layer depletion along with the growing worldwide demand for heating and cooling have brought an increasing attention toward ecological and efficient Heating, Ventilation, and Air Conditioning (HVAC) systems. Furthermore, since space heating accounts for a considerable part of the European primary/final energy use, it has been identified as one of the sectors with the most challenging targets in energy use reduction. Heat pumps are commonly considered as a technology able to contribute to the achievement of the targets. Current research focuses on the full load operation and seasonal performance assessment of three gas-driven absorption heat pump cycles. To do this, investigations of the gas-driven air-source ammonia-water absorption heat pump systems for small-scale space heating applications are presented. For each of the presented cycles, both full-load under various temperature conditions and seasonal performances are predicted by means of numerical simulations. It has been considered that small capacity appliances are usually equipped with fixed geometry restrictors, meaning that the solution mass flow rate is driven by the pressure difference across the associated restrictor valve. Results show that gas utilization efficiency (GUE) of the cycles varies between 1.2 and 1.7 for both full and partial loads and vapor exchange (VX) cycle is found to achieve the highest efficiency. It is noticed that, for typical space heating applications, heat pumps operate over a wide range of capacities and thermal lifts. Thus, partially, the novelty introduced in the paper is the investigation based on a seasonal performance approach, following the method prescribed in a recent European standard (EN 12309). The overall result is a modest variation in the seasonal performance for analyzed cycles, from 1.427 (single-effect) to 1.493 (vapor-exchange).

Keywords: absorption cycles, gas utilization efficiency, heat pump, seasonal performance, vapor exchange cycle

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3852 Energy Trading for Cooperative Microgrids with Renewable Energy Resources

Authors: Ziaullah, Shah Wahab Ali

Abstract:

Micro-grid equipped with heterogeneous energy resources present the idea of small scale distributed energy management (DEM). DEM helps in minimizing the transmission and operation costs, power management and peak load demands. Micro-grids are collections of small, independent controllable power-generating units and renewable energy resources. Micro-grids also motivate to enable active customer participation by giving accessibility of real-time information and control to the customer. The capability of fast restoration against faulty situation, integration of renewable energy resources and Information and Communication Technologies (ICT) make micro-grid as an ideal system for distributed power systems. Micro-grids can have a bank of energy storage devices. The energy management system of micro-grid can perform real-time energy forecasting of renewable resources, energy storage elements and controllable loads in making proper short-term scheduling to minimize total operating costs. We present a review of existing micro-grids optimization objectives/goals, constraints, solution approaches and tools used in micro-grids for energy management. Cost-benefit analysis of micro-grid reveals that cooperation among different micro-grids can play a vital role in the reduction of import energy cost and system stability. Cooperative micro-grids energy trading is an approach to electrical distribution energy resources that allows local energy demands more control over the optimization of power resources and uses. Cooperation among different micro-grids brings the interconnectivity and power trading issues. According to the literature, it shows that open area of research is available for cooperative micro-grids energy trading. In this paper, we proposed and formulated the efficient energy management/trading module for interconnected micro-grids. It is believed that this research will open new directions in future for energy trading in cooperative micro-grids/interconnected micro-grids.

Keywords: distributed energy management, information and communication technologies, microgrid, energy management

Procedia PDF Downloads 375
3851 Using Multiomic Plasma Profiling From Liquid Biopsies to Identify Potential Signatures for Disease Diagnostics in Late-Stage Non-small Cell Lung Cancer (NSCLC) in Trinidad and Tobago

Authors: Nicole Ramlachan, Samuel Mark West

Abstract:

Lung cancer is the leading cause of cancer-associated deaths in North America, with the vast majority being non-small cell lung cancer (NSCLC), with a five-year survival rate of only 24%. Non-invasive discovery of biomarkers associated with early-diagnosis of NSCLC can enable precision oncology efforts using liquid biopsy-based multiomics profiling of plasma. Although tissue biopsies are currently the gold standard for tumor profiling, this method presents many limitations since these are invasive, risky, and sometimes hard to obtain as well as only giving a limited tumor profile. Blood-based tests provides a less-invasive, more robust approach to interrogate both tumor- and non-tumor-derived signals. We intend to examine 30 stage III-IV NSCLC patients pre-surgery and collect plasma samples.Cell-free DNA (cfDNA) will be extracted from plasma, and next-generation sequencing (NGS) performed. Through the analysis of tumor-specific alterations, including single nucleotide variants (SNVs), insertions, deletions, copy number variations (CNVs), and methylation alterations, we intend to identify tumor-derived DNA—ctDNA among the total pool of cfDNA. This would generate data to be used as an accurate form of cancer genotyping for diagnostic purposes. Using liquid biopsies offer opportunities to improve the surveillance of cancer patients during treatment and would supplement current diagnosis and tumor profiling strategies previously not readily available in Trinidad and Tobago. It would be useful and advantageous to use this in diagnosis and tumour profiling as well as to monitor cancer patients, providing early information regarding disease evolution and treatment efficacy, and reorient treatment strategies in, timethereby improving clinical oncology outcomes.

Keywords: genomics, multiomics, clinical genetics, genotyping, oncology, diagnostics

Procedia PDF Downloads 162
3850 Studies on Non-Isothermal Crystallization Kinetics of PP/SEBS-g-MA Blends

Authors: Rishi Sharma, S. N. Maiti

Abstract:

The non-isothermal crystallization kinetics of PP/SEBS-g-MA blends up to 0-50% concentration of copolymer was studied by differential scanning calorimetry at four different cooling rates. Crystallization parameters were analyzed by Avrami and Jeziorny models. Primary and secondary crystallization processes were described by Avrami equation. Avrami model showed that all types of shapes grow from small dimensions during primary crystallization. However, three-dimensional crystal growth was observed during the secondary crystallization process. The crystallization peak and onset temperature decrease, however

Keywords: crystallization kinetics, non-isothermal, polypropylene, SEBS-g-MA

Procedia PDF Downloads 623
3849 The Challenges of Unemployment Situation and Trends in Nigeria

Authors: Simon Oga Egboja

Abstract:

In Africa, particularly in Nigeria, unemployment is a serious issue of concern to every citizen. Hence, this paper focuses on the employment situation and trends in Nigeria. It also investigated the causes why unemployment persists in the country. Prominent among them is the population explosion and rapid expansion of education opportunities all over the country without a corresponding increase in industrial establishment. The paper also discusses the way of reducing the rate of unemployment by encouraging graduates of tertiary institutions in Nigeria to read professional courses and also to indulge in the habit of establishing small-scale enterprises so that after them school they can be self-employed rather than relying solely on government for employment.

Keywords: causes, population, remedy, unemployment

Procedia PDF Downloads 274
3848 Placencia Belize: An Alternative to the Development of “Your Private Paradise”

Authors: Ryan Tao

Abstract:

This paper analyzes the local context and effects of tourism on Placencia in Belize to identify key environmental and social impacts. Placencia was a small, sleepy coastal fishing village at risk of losing its local identity to tourism. In the last decade, tourism has driven an economic shift from fishing to tourism. The consequence of this shift has eroded local environmental resources and diluted local cultural heritage. A key example is Harvest Caye, an island converted from a natural manatee breeding ground to a stereotypical sandy beach and palm tree resort complex. The incoming cruise ship-geared development of Harvest Caye reflects the urban tourist vision of Placencia’s local landscape, which indicates a “neo-colonial” rule. Consequently, this vision causes environmental destruction, replacing local memories of abundant manatee-filled waters. The paper will explore environmental and cultural damage from uncontrolled development by focusing on how Placencia has been affected by unmanaged tourism. It will then propose solutions to create a medium between tourism and the local community. New developments in other Belizean cities, such as Belmopan and Belize City, are planned at the time of approval to be sensitive to their setting. While Placencia is fully built out, there are opportunities to plan in advance for the future while preserving local integrity. As a consequence of time, shepherding tourist development, defining tourist areas, and planning these areas with an eye towards natural disasters (such as hurricanes) can act as a tool to craft a future vision that helps preserve the local identity of Placencia. This research will consist of personal observations, case studies, and synthesis of other source materials. These sources provide guidance for creating a framework to understand the local environment and culture and plan around it to ultimately protect Placencia from becoming “Your Private Paradise” for the rich.

Keywords: Placencia, coastal development, coastal protection, tourism, zoning, coastal zoning, Caribbean, Belize, small island developing states

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3847 Urban Impervious and its Impact on Storm Water Drainage Systems

Authors: Ratul Das, Udit Narayan Das

Abstract:

Surface imperviousness in urban area brings significant changes in storm water drainage systems and some recent studies reveals that the impervious surfaces that passes the storm water runoff directly to drainage systems through storm water collection systems, called directly connected impervious area (DCIA) is an effective parameter rather than total impervious areas (TIA) for computation of surface runoff. In the present study, extension of DCIA and TIA were computed for a small sub-urban area of Agartala, the capital of state Tripura. Total impervious surfaces covering the study area were identified on the existing storm water drainage map from landuse map of the study area in association with field assessments. Also, DCIA assessed through field survey were compared to DCIA computed by empirical relationships provided by other investigators. For the assessment of DCIA in the study area two methods were adopted. First, partitioning the study area into four drainage sub-zones based on average basin slope and laying of existing storm water drainage systems. In the second method, the entire study area was divided into small grids. Each grid or parcel comprised of 20m× 20m area. Total impervious surfaces were delineated from landuse map in association with on-site assessments for efficient determination of DCIA within each sub-area and grid. There was a wide variation in percent connectivity of TIA across each sub-drainage zone and grid. In the present study, total impervious area comprises 36.23% of the study area, in which 21.85% of the total study area is connected to storm water collection systems. Total pervious area (TPA) and others comprise 53.20% and 10.56% of the total area, respectively. TIA recorded by field assessment (36.23%) was considerably higher than that calculated from the available land use map (22%). From the analysis of recoded data, it is observed that the average percentage of connectivity (% DCIA with respect to TIA) is 60.31 %. The analysis also reveals that the observed DCIA lies below the line of optimal impervious surface connectivity for a sub-urban area provided by other investigators and which indicate the probable reason of water logging conditions in many parts of the study area during monsoon period.

Keywords: Drainage, imperviousness, runoff, storm water.

Procedia PDF Downloads 351
3846 Vortex Generation to Model the Airflow Downstream of a Piezoelectric Fan Array

Authors: Alastair Hales, Xi Jiang, Siming Zhang

Abstract:

Numerical methods are used to generate vortices in a domain. Through considered design, two counter-rotating vortices may interact and effectively drive one another downstream. This phenomenon is comparable to the vortex interaction that occurs in a region immediately downstream from two counter-oscillating piezoelectric (PE) fan blades. PE fans are small blades clamped at one end and driven to oscillate at their first natural frequency by an extremely low powered actuator. In operation, the high oscillation amplitude and frequency generate sufficient blade tip speed through the surrounding air to create downstream air flow. PE fans are considered an ideal solution for low power hot spot cooling in a range of small electronic devices, but a single blade does not typically induce enough air flow to be considered a direct alternative to conventional air movers, such as axial fans. The development of face-to-face PE fan arrays containing multiple blades oscillating in counter-phase to one another is essential for expanding the range of potential PE fan applications regarding the cooling of power electronics. Even in an unoptimised state, these arrays are capable of moving air volumes comparable to axial fans with less than 50% of the power demand. Replicating the airflow generated by face-to-face PE fan arrays without including the actual blades in the model reduces the process’s computational demands and enhances the rate of innovation and development in the field. Vortices are generated at a defined inlet using a time-dependent velocity profile function, which pulsates the inlet air velocity magnitude. This induces vortex generation in the considered domain, and these vortices are shown to separate and propagate downstream in a regular manner. The generation and propagation of a single vortex are compared to an equivalent vortex generated from a PE fan blade in a previous experimental investigation. Vortex separation is found to be accurately replicated in the present numerical model. Additionally, the downstream trajectory of the vortices’ centres vary by just 10.5%, and size and strength of the vortices differ by a maximum of 10.6%. Through non-dimensionalisation, the numerical method is shown to be valid for PE fan blades with differing parameters to the specific case investigated. The thorough validation methods presented verify that the numerical model may be used to replicate vortex formation from an oscillating PE fans blade. An investigation is carried out to evaluate the effects of varying the distance between two PE fan blade, pitch. At small pitch, the vorticity in the domain is maximised, along with turbulence in the near vicinity of the inlet zones. It is proposed that face-to-face PE fan arrays, oscillating in counter-phase, should have a minimal pitch to optimally cool nearby heat sources. On the other hand, downstream airflow is maximised at a larger pitch, where the vortices can fully form and effectively drive one another downstream. As such, this should be implemented when bulk airflow generation is the desired result.

Keywords: piezoelectric fans, low energy cooling, vortex formation, computational fluid dynamics

Procedia PDF Downloads 185