bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of Combustion Chamber Performance Utilizing Biochar from Empty Fruit Bunch (EFB) as Fuel with Variation in Excess Air
Authors: Bin Nur Taufiq , Zafran Hanif Muhammad , Purnomo Wibowo Rulianda , Sembiring Mariani
Published: May 2024

Palm oil mill waste is abundantly available in Indonesia as biomass. However, the inorganic part of biomass fuels causes problems related to the ash generated, leading to slagging and fouling. The slagging and fouling as deposits form on heat transfer surfaces is one of the main problems associated with biomass combustion. Reducing the deposit formation will improve the boiler’s performance. As low-calorific biomass energy, the empty fruit bunch (EFB) can be converted into high-calorific biomass solid fuel as biochar using pyrolysis. This study investigates the potential of biochar as a solid fuel that can be used as a mixed fuel with coal (cofiring) in boilers in power plants. Biochar, produced from the pyrolysis of EFB at a temperature of 500 °C, is used as fuel in the combustion chamber of a laboratory-scale boiler. The variations in excess combustion air from 20% to 40% were implemented to analyze the slagging and fouling index as well as the efficiency of the combustion chamber. From analysis, the highest combustion chamber temperature appears at 30% excess air, and the lowest was at 20%. The biochar with 30% excess air combustion has a lower potential for slagging and fouling formation. Moreover, the highest combustion chamber efficiency is around 88.06%.
Effect of Pyrolysis Temperature and Adhesive Type on the Quality of Biobriquette from Coffee Stem Biomass
Authors: Hasibuan Rosdanelli , Hidayati Juliza , Misran Erni , Permata Sari Purba Intan , Erlangga Fauzan , Pramananda Viqry , Fahira Siregar Fatimah
Published: May 2024

Biobriquette is organic waste charcoal printed in such a way that has a high energy density and calorific value. The biobriquette quality is influenced by several factors, including the pyrolysis temperature and the adhesive type. This research aims to evaluate the effect of pyrolysis temperature (250°C, 300°C, and 350°C) and adhesive type (tapioca, molasses, and a tapioca-molasses mixture) on the quality of biobriquette from coffee stem. This research steps include pyrolysis of coffee stem, biobriquette production, and quality analysis of biobriquette. The biobriquette quality described refers to SNI No. 01-6235-2000, including water content, ash content, volatile matter, calorific value, and additional analysis, including fixed carbon, density, compressive strength, and combustion rate. This research shows that increasing the pyrolysis temperature will increase the charcoal yield. Pyrolysis temperature and adhesive type affect the quality of biobriquette. All biobriquette produced at a pyrolysis temperature of 350°C met SNI No. 01-6235-2000, in terms of water, ash, volatile, and heating values. The best biobriquette was obtained with a pyrolysis temperature of 350°C and tapioca adhesive, with water content of 2.45%, ash content of 2.35%, volatile matter of 1.24%, density of 1,345 g/cm3, compressive strength of 91.775 kg/cm2, and a calorific value of 7,463.957 cal/g.
Sustainable Energy and Inventory Efficiency Optimization: Implementing EOQ Strategy
Authors: Panjaitan Nismah , Amalina Binti Muhammad Nur , Febe Gultom Diora , Sahfa Rizky Naila
Published: May 2024

Production represents a fundamental activity within an organization, culminating in the generation of goods or services over a given period. This outcome is then recognized as the organization’s value addition. A critical element of production is the management of raw material inventories. Accurate forecasting of these inventories is essential to preemptively manage potential shortages or excesses, which could lead to production inefficiencies. It is vital for all businesses, particularly those in the manufacturing sector, to work closely with their suppliers to secure a consistent supply of raw materials. Keeping raw material inventory at an optimal level is paramount; insufficient stock can halt production, resulting in lower sales and customer dissatisfaction. This situation adversely affects a company’s profitability and diminishes consumer confidence. Inventory’s primary function within a system is to ensure a smooth process in meeting product demand according to consumer needs, thereby allowing the system to achieve peak efficiency. Moreover, adept inventory management aids in curtailing production costs for a company.
Simulation of the Photovoltaic System Capacity to Power the Electrical Vehicles under Tropical Climate of Surabaya, Indonesia
Authors: Tarigan Elieser , Candra Susila , Wibowo Susilo
Published: May 2024

This paper presents a simulation study of a photovoltaic capacity to power electrical vehicle under the tropical climate of Surabaya, Indonesia. The study aims to investigate the feasibility of using solar panels as the main energy source for electrical vehicle in a tropical region, where solar radiation is abundant but often accompanied by high temperatures and humidity. The simulation model was developed using “Photovoltaic Geographical Information System” software, which integrates a mathematical model of the photovoltaic panel. The simulation was carried out over a period of one year, with weather data from simulation database. Given that electric cars have an average energy consumption of about 0.15 kWh/km, the daily electrical energy needed falls within the range of 6.0 to 7.5 kWh. Analyzing the specific data on the output energy of photovoltaic systems in Surabaya reveals that a photovoltaic system capacity of approximately 1.7 to 2.0 kWp is required to fulfill this daily energy demand.
Photovoltaics Efficiency on Automatic Fish Feeding Distributors Device Using Internet of Things
Authors: Sigalingging Riswanti , Wan Chanlyn Sigalingging Join , Alfinsyah Barus Fauzan , Harryananta Sumba
Published: May 2024

Renewable energy is crucial for facilitating the shift towards a more sustainable society. It plays a significant role in establishing a clean energy system, mitigating greenhouse gas emissions, and enhancing the well-being of both current and future generations. The study included field observation and data analysis approaches. The study utilized IoT-based automatic fish feed spreaders, photovoltaic units, batteries, SCC (solar charge controller), Android phones, thermometers, multimeter tester, LCDs, ultrasonic sensors, and a microcontroller circuit. This study aims to acquire power, electrical energy, and efficiency measurements from solar systems employed in an Internet of Things (IoT) enabled automatic fish feeder apparatus. The results show that the power consumption needed to operate the IoT-based automatic fish feeder gadget is 48.75 watts. The peak of solar irradiance was recorded at 12.00 WIT, averaging 900.27 W/m2. The lowest intensity was at 09.00 WIT, averaging 422.78 W/m2. Photovoltaics can produce electrical power at 22.75 watts per hour, leading to a daily electrical energy output of 159.25 Wh. The highest photovoltaics efficiency was 16.37% with 465.3 W/m2 of solar irradiance, 30.7°C of temperature and 2.144 m/s of wind speed. The temperature and wind speed has significantly affected on photovoltaics efficiency.
Optimizing Microgrid Efficiency with Battery and Super Capacitor Hybrid Systems
Authors: Hardi Surya , Nur Salam Rasyid , Suherman Suherman , Riadi Selamat
Published: May 2024

Microgrids are small networks consisting of several renewable energy sources such as wind light, sunlight, geothermal, bioenergy, water and so on. But the drawback of this system is in fluctuating power and when the source does not produce power at a certain time. So that power storage media such as batteries and supercapacitors are needed to maintain contingency when the source does not supply enough load. The purpose of this study was toobtain the effect of adding supercapacitors with batteries and compare battery storage media without supercapacitors. From the results of the study, it was found that the addition of supercapacitors can maintain battery stability charging from 50% State of Charge (SOC) down to 47% and start It rises back by 50% at 1 second, as well as additional charging can be set to our liking. If the battery storage media is without supercapacitors, battery charging tends to drop from 50% and continue to fall without any increaseat all. So it can be concluded that with the addition of supercapacitors are able to maintain the performance of the battery in the microgrid system.
Vapor-Liquid Equilibrium Measurement of Systems Containing Glycerol for Separation Process of Glycerol as a By-Product of Biodiesel
Authors: Cahyaning Ananda Arih , Tetrisyanda Rizky , Batutah Moh Arif , Wibawa Gede
Published: May 2024

The most popular technique to produce biodiesel were uses alcohol as a catalyst to transesterify triglycerides. The biodiesel transesterification process has a by-product in the form of glycerol which has a high selling value. Equilibrium data of glycerol and alcohol mixtures is limited in equilibrium conditions and systems which causes the glycerol purification process may not be designed and operated optimally. This research aims to obtain experimentally isobaric vapor-liquid equilibrium of methanol + glycerol binary system at 31.3, 61.3, and 100.8 kPa. A modified Glass Othmer-Still was utilised to carry out the experiment. Refractometer index type Bausch and Lomb ABBE was used to examine the equilibrium composition of the liquid and vapor phases. Using the L-W thermodynamic consistency test method, the experimental data used in this work were shown to be thermodynamically consistent. The experimental data were correlated well with the Wilson, Non-Random Two Liquid (NRTL), and Universal Quasi-Chemical (UNIQUAC) models with absolute average deviation in temperatures (AADT) and that in vapor compositions (AADy) smaller than 0.3% and 0.2%, respectively. The Universal Chemical Functional Group Activity Coefficient (UNIFAC) in predicting VLE the system studied showed good performance giving AADT and AADy smaller than 7.4% and 0.04%, respectively.
Analysis of Aerosol Removal Efficiency and Electrical Energy Consumption in the Use of Air Conditioner and Air Purifier in a Room
Authors: Syafe’i Arie Dipareza , Febriwati Melani
Published: May 2024

Indoor air quality is important for an individual's quality impacts human comfort, health, and performance. This research aims to identify the effect of variations in air conditioner (AC) temperature control systems and air purifier (AP) fan speed on PM2.5 and PM10 concentrations and recommendations for AC and AP settings to remove aerosols with high efficiency and lower electrical energy with statistical test. The highest percentage of PM2.5 and PM10 removal when the AC was set to a temperature of 22°C with the AP turned on automatically, namely 89.7% in removing PM2.5 and 90.98% in removing PM10. The lowest percentage of removal of PM2.5 and PM10 concentrations when the AC temperature was set to be turned on at 25°C with the AP set turned off, namely 40.57%. The first recommendation is to set the AC to be turned on at 25°C and the AP to be turned on automatically for using 80 minutes, which has a percentage of 84.8% with a price of 17,400 IDR/month. The second condition that can be recommended is setting the AP to be turned on automatically, but the AC set turned off, which has a percentage of 89.29% for 1,800 IDR/month.
Geophysical and Geochemical Approach for Seawater Intrusion Assessment in the Belawan Coast and the Medan Industrial Area, North Sumatera Utara, Indonesia
Authors: Muzambiq Said , Sarah Maya , Khair Hafizul , Yasa Ardiansyah Edi , Adhari Heri , Hidayati  , Huda Adri , Harpah Hasibuan Novrida
Published: May 2024

The uncontrolled underground water exploitation and inadequate domestic and industrial wastewater control systems have contributed significantly to groundwater degradation. The groundwater degradation potentially initiates the seawater intrusion especially on the coastal area. The present study aims to analyze the seawater intrusion using geophysical and geochemical approach in the coastal area of Belawan and Medan Industrial Area which close to the coastal area. 15 borehole water samples collected were analyzed to determine anions, cations concentrations, and facies. The results showed that the lithostratigraphy of the study area consisted of alluvial in form of watery gravel and clay layers. The investigation of the groundwater using the geoelectricmethod showed that the resistivity values for track 1 (GL-1) and track (GL-02) are 129Ω to 371Ω. These values are interpreted as layers of sand that have experienced seawater intrusion at a depth of 40-60 meters. Furthermore, the water quality tests at the point of wells 1 and 2 on the chloride parameter, where the highest chloride concentration with values of 205.8 mg/l and 203.2 mg/l, was polluted. The result proved that the seawater intrusion has stimulated the groundwater in the coastal area of Belawan and Medan Industrial Area, Indonesia.
Microplastic Distribution Model in Ambient Air PM2.5 Around the Medan Industrial Area, North Sumatra
Authors: Suryati Isra’ , Harpah Hasibuan Novrida , Angella Silalahi Rina , Malau Romian , Tambun Yolanda
Published: May 2024

This research aims to investigate and model the distribution of microplastics in PM2.5-sized air particulates around the Medan industrial area, North Sumatra. Focusing on airborne particles less than 2.5 micrometers in diameter, this research seeks to understand the impact of exposure to microplastics on ambient air quality. The air sampling method was carried out systematically at various strategic points around the industrial area, and laboratory analysis was carried out to detect and identify microplastics. The research results showed that the number of microplastics in PM2.5 in ambient air ranged from 41 – 92 particles with an abundance of 0.41 – 1.40 particles/m3. The dominant form of microplastics around the Medan industrial area is fragments, amounting to 62%. The distribution of the number of microplastics and their abundance is marked in red, which is close to the source of pollution, namely industrial areas.
Analysis Distribution of Iron (Fe) and Hexavalent Chromium (Cr6+) Contaminants in Shallow Groundwater Due To Leachate Around Landfill Terjun, Medan City
Authors: Siregar Ronald , Tanjung Munir , Roselina Tresa , Arbi Yaumal
Published: May 2024

Terjun Landfill Area is currently in a transition period from an open dumping system to a sanitary landfill. The resulting leachate can spread through infiltration into the soil. Leachate seepage into groundwater will affect groundwater quality. This research aims to analyze the distribution of iron (Fe) and hexavalent chromium (Cr6+) contaminants in shallow groundwater resulting from leachate around the Terjun Landfill Area. Model simulations were carried out using the Domenico Robbins (1990) model using the MathLab. The results show that the metal pollutants Fe and Cr6+ in residents’ wells have exceeded the quality standards in Minister of Health Regulation Number 2 of 2023. The results show that the pollutants Fe and Cr6+ have spread up to > 700 m from the landfill. Fe contamination in the estimated 40 years since the landfill operated was spread over a distance of 750 meters with a pollutant concentration of 0.066 mg/L, and in 50 years it increased to 0.092 mg/L. Meanwhile Cr6+ contamination over a period of 40 years at a distance of 750 meters spread with a concentration of 0.426 mg/L and increased in the 50th year by 0.600 mg/L.
Analysis of lashing gear in ship loading spaces to meet safety transportation
Authors: Tampubolon Freddy , Seno William , Sarjana Sri
Published: May 2024

Merak and Bakauheni Ferry Ports are two port nodes for the Merak - Bakauheni Ferry Crossing. Both are the main bridges connecting Java Island and Sumatra Island. This research aims to analyze the implementation of the obligation to tie vehicles (lashing gear) in the loading space of ships on the Merak - Bakauheni crossing. The expected aim of this study is to determine the suitability of the implementation of the two ministerial regulations. The analysis utilizes three methods: (1) the analysis of the transportation of vehicles on board, (2) the analysis of the distance between vehicles, and (3) the analysis of vehicle tie-up officers. The results of this study state that the loading of vehicles on the crossing on the Merak - Bakauheni track is still not in accordance with the loading procedures regulated in the Minister of Transportation Regulation Number 115 of 2016 because there are still rules that are not implemented during the process of transporting vehicles on board There are still several lashing officers at the Merak-Bakauheni port who do not have sufficient knowledge and experience regarding technical regulations and lashing gear procedures. Therefore, it is deemed necessary to conduct regular training or socialization sessions.
Building for tomorrow: A green building approach to children and youth activity center in Medan City
Authors: Lubis M. D. , Michkael Jason , Bertha Winsti Elisa , Affif Aulia Malik
Published: May 2024

The rapid urbanization in North Sumatra, particularly in Medan, poses significant challenges to the well-being of children and youths due to increased industrial activities and traffic, leading to heightened air and noise pollution levels. The “Building for Tomorrow” concept emphasizes a green building approach for a children and youth activity center in Medan. The study employs qualitative and descriptive methods, including surveys and analysis based on green building parameters by the Green Building Council Indonesia. The proposed center aims to provide a safe, healthy, and stimulating environment to counteract the adverse impacts of urbanization, prioritizing the well-being of younger generations and fostering environmental consciousness. The key design aspects of this study focus on Appropriate Site Development, Energy Efficiency, Water Conservation, Material Resource and Cycle, Indoor Health and Comfort, and Building Environment Management, while offering essential facilities such as education, sports, open spaces, art centers, cafes, and toilets. By meeting green building standards, the center aims to contribute to a healthier environment for future generations in Medan
Flood Risk Reduction Strategy With Vertical Drainage In Medan City, Indonesia
Authors: Novrial  , Thayah Awaluddin , Rahman N. Vinky , Purba Nuraliya
Published: May 2024

As the population of a city increases, there will be excessive exploitation of nature, uncontrolled land use change, and a decrease in the environment’s carrying capacity. These impacts cause flood disasters to increase in quantity and quality. Floods are still difficult to predict and avoid. Medan City is still haunted by the same problem as other cities in Indonesia, namely flooding. The government has focused on flood management by building a horizontal drainage network system, normalizing rivers, building embankments, but flooding still occurs frequently. Therefore, vertical drainage is needed for flood management. Vertical drainage drains surface water directly into the soil layer that horizontal drainage cannot accommodate. This research aims to study the ability of vertical drainage in Medan City to reduce flood risk. Based on the test results, vertical drainage has a discharge of 0.812 liters/second. Based on technical calculations, vertical drainage can distribute potential rainwater collected on the surface and with the addition of possible water from other sources at the research site within 9 minutes 1 second until it runs out as much as 440 liters. As a result, one vertical drainage system can effectively accommodate an area of 25 m2.
Evaluation of Sustainable Architecture Principles Application in Recycling Mall (Case Study: ReTuna Återbruksgalleria)
Authors: Andrea Sembiring Dicky , Rizqullah Ananda
Published: May 2024

This study examines the role of sustainable architecture in waste management, using Sweden’s ReTuna Återbruksgalleria, a recycling mall, as a key example. It highlights how sustainable design can address environmental issues by incorporating urban ecology, energy conservation, water management, waste reduction, and community engagement. ReTuna is celebrated for its innovative approach to reducing waste, repurposing materials, stimulating the economy, raising environmental consciousness, and collaborating with locals. The research delves into sustainable architecture’s complexities, especially in waste management, by reviewing extensive literature to offer a comprehensive view. It underscores the importance of eco-friendly practices beyond academic circles, aiming to motivate various sectors to act. The insights gained aspire to shape a globally sustainable, environmentally mindful built environment.
Comparative study of mathematical and experimental models of coffee bean drying rate in a solar dryer simulator
Authors: Sihombing H. V. , Ambarita H. , Silalahi J. F.
Published: May 2024

The drying process of coffee beans requires heat energy to evaporate the moisture content in the material to be dried. Arabica coffee is dried at controlled temperatures (50°C, 60°C and 70°C) and wind speeds (0.4 m/s, 0.8 m/s and 1 m/s). The initial moisture content of the coffee bean test of 70% was dried to a moisture content of 11%. The drying air temperature is important for drying at high temperatures using a solar dryer simulator, which results in rapid moisture removal and reduced drying time. Drying was carried out to obtain the rate of reduction of moisture content experimentally compared to theoretically on mathematical models of drying agricultural products (Newton, Modified Henderson and Pabis and Modified Midili). Drying parameters are related to mass loss, temperature and humidity. From the results of the calculation of the experimental water content reduction rate with 3 formulas, the closest equation is Modified Midili.
Natural Growth Model of Amorphophallus gigas from Simandiangin Hamlet, Sungai Kanan District, North Sumatra
Authors: Sorta Mauli Nababan Esther , Rambey Ridahati , Rahmawaty  , Rauf Abdul , Delvian  , Aththorick T. Alief , Ismail Mohd Hasmadi , Saputra Muhammad Hadi , Gandaseca Seca , Suratman Mohd Nazip
Published: May 2024

Amorphophallus gigas is a plant belonging to the Araceae family, including the tallest flower in the world. A. gigas was often found in North Sumatra, grows naturally under agroforestry stands. The aim of this research was to calculate the population of A. gigas and predict the population of A. gigas in the future assuming the habitat is not disturbed. This research was conducted in Simandiangin Hamlet, South Labuhanbatu Regency, North Sumatra Indonesia. The method used is to count the number of A. gigas individuals in 1 hectare by census. From the research results, there were 92 Amorphopallus gigas individuals with various growth phases, 40 seedlings, 28 juveniles and 26 adults. The average seedling height is 7.52 cm, the average seedling diameter is 0.27 cm, the average number of leaves is 7, the average canopy width is 27.27 cm. The average height in the juvenile phase is 56.88 cm, the average diameter is 1.40 cm and the canopy width is 76.2 cm. The average height in the adult phase is 151 cm, diameter 5.36, number of leaves 132 and canopy width 199.08 cm.
Effect of Cutting Size in the Composting Process of Oil Palm Empty Fruit Branches (EFB) Using Active Organic Liquid Fertilizer (AOLF) as Co-Composting
Authors: Sidabutar Rivaldi , Trisakti Bambang , Irvan H. , Syafrizal Muhammad , Alamsyah Vandria , Passa Raissa , Aginta Sitepu Rafael
Published: May 2024

The size of organic waste materials plays a pivotal role in the composting process, influencing parameters such as decomposition rate, microbial activity, aeration, and nutrient availability. Currently, the study of compost has focused on the degradatiom of organic matter. The study began by varying the sizes of oil palm EFB to 1-3, 3-5, and 5-7 cm. Subsequently, the EFB were placed into a basket composter (33 cm length x 23 cm width x 40 cm height), and active organic liquid fertilizer was added to achieve a moisture content of around 55-65%. The observation period lasted for 60 days. Throughout the composting process, the moisture content was maintained at 55-65% by adding active organic liquid fertilizer, and the composter was turned every 3 days. Analyzed parameters during the composting process included temperature, pH, volatile suspended solids, electrical conductivity, and water holding capacity. The best results were obtained with a cutting size of 3-5 cm, yielding the following values: temperature 26.75 °C, pH 7.5, volatile suspended solids 211,640 mg/L, electrical conductivity 4.05 dS/m, and water holding capacity 65%.
Measurement of the coupling of magnetism with electricity or light irradiation in BiFeO3 using the Kerr angle
Authors: Polin Siwat , Laohana Peerawat , Kullapapinyokol Jirapat , Jindata Warakorn , Musikajaroen Supansa , Rasritat Aissara , Nakajima Hideki , Saenrang Wittawat , Maensiri Santi , Eom Chang-Beom , Meevasana Worawat
Published: May 2024

The magneto-optical Kerr effect (MOKE) in monodomain bismuth ferrite (BiFeO3) thin films was investigated under applied electric fields and light irradiation. The field-swept MOKE measurements show that the Kerr rotation of BiFeO3 changes under applied electric fields or light irradiation. The piezoresponse force microscopy measurements found that the variation in electrical polarization at the BiFeO3 surface was similar under an applied electric field and ultraviolet irradiation, confirming that the Kerr rotation of BiFeO3 can be controlled using both electric fields and light irradiation. This paper presents a method to couple a magnetic field with an electric field or light irradiation via the Kerr angle measurements of BiFeO3, providing a concept for fabricating multifunctional devices in oxide electronics.
Bond-selective effect for the dissociative chemisorption of HOD on the Ni(100) surface revealed at the full-dimensional quantum dynamical level
Authors: Liu Tianhui , Fu Bina , Zhang Dong H.
Published: May 2024

We present a comprehensive investigation into the dissociative chemisorption of HOD on a rigid Ni(100) surface using an approximate full-dimensional (9D) quantum dynamics approach, which was based on the time-dependent wave-packet calculations on a full-dimensional potential energy surface obtained through neural network fitting to density functional theory energy points. The approximate-9D probabilities were computed by averaging the seven-dimensional (7D) site-specific dissociation probabilities across six impact sites with appropriate relative weights. Our results uncover a distinctive bond-selective effect, demonstrating that the vibrational excitation of a specific bond substantially enhances the cleavage of that excited bond. The product branching ratios are substantially influenced by which bond undergoes excitation, exhibiting a clear preference for the product formed through the cleavage of the excited bond over the alternative product.
Rate theory of gas–liquid nucleation: Quest for the elusive quantitative accuracy
Authors: Acharya Subhajit , Bagchi Biman
Published: May 2024

The task of a first principles theoretical calculation of the rate of gas–liquid nucleation has remained largely incomplete despite the existence of reliable results from unbiased simulation studies at large supersaturation. Although the classical nucleation theory formulated by Becker–Doring–Zeldovich about a century ago provides an elegant, widely used picture of nucleation in a first-order phase transition, the theory finds difficulties in predicting the rate accurately, especially in the case of gas-to-liquid nucleation. Here, we use a multiple-order parameter description to construct the nucleation free energy surface needed to calculate the nucleation rate. A multidimensional non-Markovian (MDNM) rate theory formulation that generalizes Langer’s well-known nucleation theory by using the Grote–Hynes MDNM treatment is used to obtain the rate of barrier crossing. We find good agreement of the theory with the rate obtained by direct unbiased molecular dynamics simulations—the latter is feasible at large supersaturation, S. The theory gives an experimentally strong dependence of the rate of nucleation on supersaturation, S. Interestingly, we find a strong influence of the frequency-dependent friction coefficient at the barrier top. This arises from multiple recrossings of the barrier surface. We find that a Markovian theory, such as Langer’s formulation, fails to capture the rate quantitatively. In addition, the multidimensional transition state theory expression performs poorly, revealing the underlying role of the friction coefficient.
Rapid modulation of left- and right-handed optical vortices for precise measurements of helical dichroism
Authors: Hashiyada Shun , Tanaka Yoshito Y.
Published: May 2024

Helical dichroism (HD), which is defined as the difference in optical absorption between chiral pairs of lights involving left-handed (LH) and right-handed (RH) optical vortices (OVs) carrying orbital angular momentum (OAM), is a promising way to characterize chiral materials. In the current major methods of OV generation using spatial light modulators (SLMs), the speed of OAM switching is typically as slow as 100 Hz, which is comparable to low-frequency noise, making precise chiral detection difficult. Here, we theoretically propose and experimentally demonstrate a rapid modulation of the LH and RH OVs at around 50 kHz. This modulation is achieved through a rapid modulation of circularly polarized lights carrying spin angular momentum (SAM), combined with a SAM–OAM conversion technique. We establish a theory not only for rapid OV modulation but also for HD measurements using the modulated OVs. We experimentally verify the theory using helical phase holograms drawn on a SLM as a pseudo-HD active sample. Our work addresses the limitations of current methods and offers a new avenue for precise HD measurements, paving the way for the development of sensitive chiral-optical spectroscopy techniques.
An all-in-one device creates and characterizes high-pressure superconductors
Authors: Miller Johanna L.
Published: May 2024

Diamond has the ability to squeeze materials to immense pressures and to measure their magnetic properties. Now it can do both at the same time.
Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: personnel dose assessment
Authors: Ioannidou SP , Katsouli M , Doika E
Published: May 2024

The role of 18F–fluoro–deoxy–glucose in positron emission tomography (PET) imaging is well established in diagnosis and management of cancer patients. Installations of on-site self-shielded mini cyclotrons are increasing. The Dose on Demand Biomarker Generator BG-75 was installed at Metaxa Cancer Hospital, Greece, in May 2021 and is the first hospital-based PET radiopharmaceutical cyclotron in the country. Personnel expected external exposure was established during commissioning; internal exposure is not expected. Personnel dose was estimated with two methods: survey meter measurements in various locations combined with the time spent in each location, and direct measurement using electronic personal dosemeters. Gamma and neutron radiation readings outside the cyclotron vault were at background levels. Inside the cyclotron vault, the highest recorded radiation readings by the target were 18 μSv h−1 for both gammas and neutrons with cyclotron in operational mode; at one meter, the values were 5 μSv h−1 and 4 μSv h−1, respectively. The annual expected whole body dose per cyclotron operator is 0.6 mSv, and the respective extremity dose 16 mSv. The annual expected whole body and extremity dose for the radiochemist is 0.3 mSv and 25 mSv, respectively. The respective annual dose estimates for the medical physicists are < 1 mSv. The expected personnel doses are well below the regulatory limits and local as low as reasonably achievable (ALARA) levels. With experience and a robust ALARA program, personnel exposure could be further reduced.
Fostering scientific methods in simulations through symbolic regressions
Authors: Llorella Fabio , Antonio Cebrián José , Corbi Alberto , María Pérez Antonio
Published: May 2024

Two-dimensional computer and tablet PC physics simulations have proved to be effective in helping students understand the fundamental principles of physics and related natural processes. However, the current approach to using these simulations tends to follow a repetitive cognitive and procedural pathway, regardless of the specific physical concepts being explored or software environment being used. This approach involves manipulating the simulation interface and collecting data through interaction with controls, widgets, or other contextual elements. Students then attempt to determine how these experimental measurements align with established laws, interactions, or mechanisms, as the teacher might have previously explained. We believe that this approach, while appropriate for education, obscures scientific processes, mainly related to the hypothetico-deductive model. To address this issue, we have developed a simple and adaptable computer environment that makes use of genetic algorithms (GAs) and symbolic regression to derive many of the basic laws of nature from the data collected by students using the popular physics education technology (PhET) simulations environment. Our proposal enables learners to observe how the order and relationships of mathematical tokens are routinely refined as new data points are added to the simulation setting. This iterative distillation technique can also be augmented with the interplay of dimensional analysis. In contrast with other more sophisticated artificial intelligence patterns, GA fit into the realm of grey box machine learning models. These type of evolutionary algorithms achieve the sought results by evolving mathematical models on each stage in an understandable way, which mimics the way scientific breakthroughs are accomplished (over the course of generations of researchers and based of prior knowledge). By implementing this innovative approach, we can provide students with a more authentic empirical experience that fosters a deeper understanding of the principles of science and scientific discovery. Field tests with students supporting this claim have also been carried out.
Dissipative processes at the acoustic horizon
Authors: Chiofalo Maria Luisa , Grasso Dario , Mannarelli Massimo , Trabucco Silvia
Published: May 2024

A transonic fluid flow generates an acoustic hole that is the hydrodynamic analogue of a gravitational black hole (BH). Acoustic holes emit a detectable thermal radiation of phonons at a characteristic Hawking temperature. The crucial concept is that the spontaneous phonon emission at the horizon produces an irreversible heat increase at the expenses of the bulk fluid kinetic energy. We show that such process can be described in terms ofeffectiveshear and bulk viscosities that are defined close to the horizon. We analyze this quantum friction process by resorting to a general kinetic theory approach as well as by the specific description of phonon emission as a tunneling process. The celebrated Kovtun, Son and Starinets (KSS) universal lower boundη/s=1/4πof the shear viscosity coefficient to entropy density ratio, readily follows, and is extended to the longitudinal bulk viscosity at the horizon. We come to the same saturation of the KSS bound after considering the shear viscosity arising from a perturbation of the background metric at the acoustic horizon providing a—in principle testable—realization of the so called BHmembrane paradigm.
Long term variation of microphysical properties of black carbon in Beijing derived from observation and machine learning
Authors: Hu Kang , Liu Dantong , Li Siyuan , Wu Yangzhou , Pan Baiwan , Zhao Shitong , Jiang Xiaotong , Ding Shuo , Tian Ping , Hu Dawei , Yu Chenjie , Wang Ye , Wang Fei , Zhao Delong , Wu Yunfei , Ding Deping , liao Hong
Published: May 2024

The microphysical attributes of black carbon (BC) can determine its absorption and hygroscopic properties. However, long-term information is difficult to obtain from the field. In this study, the BC properties including mass concentration, the coating volume ratio (VR) relative to the refractory BC (rBC), the rBC diameter and the fraction of cloud condensation nuclei (CCN), are derived from a number of field experiments using a random forest model. This model effectively derives the long-term BC microphysical properties in the Beijing region from 2013 to 2020 using continuous measurements of particulate matter, gas, BC mass concentration and meteorological parameters. The results reveal notably higher BC coatings (mean VR = 7.2) and a greater fraction of CCN-like BC (51%) in the winter compared to other seasons. Following the implementation of national air pollution control measures in 2017, BC mass exhibited a substantial reduction of 60% (29%) in the winter (summer), and VR decreased by 45% (24%). Apart from the influence of meteorological variations, these can be attributed to the declined primary emissions and the gas precursors which are associated with secondary formation of BC coatings. The reduction of both BC mass loading and coatings leads to its solar absorption decreasing by 50%, and the fraction of CCN-like BC (likely in clouds) decreasing by 23%. Environmental regulation will therefore continue to reduce both direct and indirect radiative impacts of BC in this region.
Kernel-summability methods and the Silverman–Toeplitz Theorem
Authors: Parisé Pierre-Olivier
Published: May 2024

We introduce kernel-summability methods in Banach spaces using vector-valued integrals and prove an analogue of the Silverman–Toeplitz Theorem. We also show that inclusion of kernel-summability methods for scalar-valued functions implies inclusion for vector-valued functions. This extends a previous result from Mashreghi, Ransford and the author. We then apply these abstract results to the summability of Taylor series of functions in a Banach space of holomorphic functions on the unit disk.
On the generation of simple groups by Sylow subgroups
Authors: Burness Timothy , Guralnick Robert
Published: May 2024

Let

G
G

be a finite simple group of Lie type and let

P
P

be a Sylow

2
2

-subgroup of

G
G

. In this paper, we prove that for any nontrivial element

x
∈
G

x \in G

, there exists

g
∈
G

g \in G

such that

G
=
⟨
P
,

x
g

⟩

G = \langle P, x^g \rangle

. By combining this result with recent work of Breuer and Guralnick, we deduce that if

G
G

is a finite nonabelian simple group and

r
r

is any prime divisor of

|

G

|

|G|

, then

G
G

is generated by a Sylow

2
2

-subgroup and a Sylow

r
r

-subgroup.
Highly versal torsors
Authors: First Uriya
Published: May 2024

Let

G
G

be a linear algebraic group over an infinite field

k
k

. Loosely speaking, a

G
G

-torsor over a

k
k

-variety is said to be versal if it specializes to every

G
G

-torsor over any

k
k

-field. The existence of versal torsors is well-known. We show that there exist

G
G

-torsors that admit even stronger versality properties. For example, for every

d
∈

N

d\in \mathbb {N}

, there exists a

G
G

-torsor over a smooth quasi-projective

k
k

-scheme that specializes to every torsor over a quasi-projective

k
k

-scheme after removing some codimension-

d
d

closed subset from the latter. Moreover, such specializations are abundant in a well-defined sense. Similar results hold if we replace

k
k

with an arbitrary base-scheme. In the course of the proof we show that every globally generated rank-

n
n

vector bundle over a

d
d

-dimensional

k
k

-scheme of finite type can be generated by

n
+
d

n+d

global sections.

When

G
G

can be embedded in a group scheme of unipotent upper-triangular matrices, we further show that there exist

G
G

-torsors specializing to every

G
G

-torsor over any affine

k
k

-scheme. We show that the converse holds when

c
h
a
r
k
=
0

chark=0

.

We apply our highly versal torsors to show that, for fixed

m
,
n
∈

N

m,n\in \mathbb {N}

, the symbol length of any degree-

m
m

period-

n
n

Azumaya algebra over any local

Z

[

1
n

,

e

2
π
i

/

n

]

\mathbb {Z}[\frac {1}{n},e^{2\pi i/n}]

-ring is uniformly bounded. A similar statement holds in the semilocal case, but under mild restrictions on the base ring.
Groups versus rings
Authors: Larsen Michael , Shalev Aner
Published: May 2024

We compare groups with rings in a range of contexts in which ring theory problems tend to be more tractable than their group theory analogues. The main topics discussed in this paper are probabilistic identities in groups, rings which are almost PI, and random generation of groups and algebras. We show, for example, that almost PI algebras are PI, while the analogous problem for groups is very much open.
Improved regularity for a Hessian-dependent functional
Authors: Bianca Vincenzo , Pimentel Edgard , Urbano José
Published: May 2024

We prove that minimizers of the

L

d

L^{d}

-norm of the Hessian in the unit ball of

R

d

\mathbb {R}^d

are locally of class

C

1
,
α

C^{1,\alpha }

. Our findings extend previous results on Hessian-dependent functionals to the borderline case and resonate with the Hölder regularity theory available for elliptic equations in double-divergence form.
The null condition for systems of nonlinear wave equations and its related topics
Authors: Katayama Soichiro
Published: May 2024

In this article, we consider the Cauchy problem for systems of nonlinear wave equations, whose nonlinear terms depend mainly on derivatives of the unknown, with small, smooth, and compactly supported initial data. If the nonlinear terms have the critical power, we need some structural conditions to obtain the small data global existence. The null condition is one such condition, but recently some weaker conditions were also found. We discuss the small data global existence and the asymptotic behavior of solutions under these conditions. The corresponding result for nonlinear Schrödinger equations will be also discussed.
History and the Study of Religion
Authors: Stowers Stanley
Published: May 2024

Against the trend to deny that religion can be a useful category for historians to use across time and cultures, the book argues that religion is a social kind, a real and relatively stable cross-cultural entity in the social world. Early chapters show how this realism about the social grows out of key developments in philosophy, cognitive psychology, and social theory. Examples from the ancient Mediterranean and ethnographic examples illustrate this usefulness for creating social theory and historical explanation. Ontological analysis of the religious subkinds provides the basis for a more complex and useful social theory of religion as a kind. In the primary test case, the book argues that the beginnings of Christianity can be explained as arising from ancient Mediterranean religion. The latter consisted of three subkinds; the religion of everyday social exchange, civic religion, and the religion of literate and literary experts. Christianity emerged from a social field of the experts in interaction with the other two subkinds so as to produce a third subkind, the religion of literate experts with political power. These latter chapters use the theory to treat questions such as the Christian movement’s success in the Roman Empire, whether it was a socially and morally superior form of religion, how it was socially constituted in comparison to other religion in the Empire, its relation to philosophy, whether it was monotheistic, and about its most fundamental social dynamics. Both epistemic causal and ontological constitutive social kinds thus show themselves to be theoretically valuable for historians and social theorists.
The Formation of Christianity
Authors: Stowers Stanley
Published: May 2024

Using the theory of social kinds, this chapter explains how Christianity emerged from ancient Mediterranean religion. The Christian movement formed within the social field of literate and literary experts in religion from its freelance or more autonomous pole in the portion of the field occupied by Judean intellectuals writing in Greek. These figures attacked everyday religiosity as superstition and civic religion as idolatry. The social form of experts with students and nonexpert followers would form the fundamental social structure that became clergy and laity. Freelance experts like Paul, Marcion, and Justin, still operating in the field with philosophers and sophists, lost ground to experts who depended more and more on locative principles. These literate experts with power over the nonexperts/laity found it impossible to fully “educate” the nonexperts and had to constantly deal with the religion of everyday social exchange that the nonexperts could not fully leave behind. The result included the need for experts to permit practices of exchange with martyrs, saints, and the beloved dead.
In Sublimity’s Wake
Authors: Bennett William
Published: May 2024

This research paper comparatively assesses Deleuze’s and Lyotard’s post-Kantian thought on the sublime. Initially, I argue that their unfaithful treatment of Kant bears consonance in dramatizing the heterogeneity of the transcendental faculties, relegating determinate thought to a subsidiary consideration, and conceiving of aesthetics as an excessive mode of production rather than a reflective form of judgement. However, they diverge in the details regarding aesthetic production in their writings on modernist painting. In conclusion, I maintain that these accounts require a paradigmatic shift in thought away from determinate judgement toward a fidelity to events. The significance of drawing these two thinkers together in this regard is in the recognition and elucidation of an event-oriented ontology, whereby the subject is actively transformed through creative responses to singular events in a process of rupture and regeneration. This rests upon the postulate that reality is not exhausted by experience, and carries with it an ethical imperative to resist limiting the future to the present conditions of experience.
Breast cancer prognosis through the use of multi-modal classifiers: current state of the art and the way forward
Authors: Mathur Archana , Arya Nikhilanand , Pasupa Kitsuchart , Saha Sriparna , Roy Dey Sudeepa , Saha Snehanshu
Published: May 2024

We present a survey of the current state-of-the-art in breast cancer detection and prognosis. We analyze the evolution of Artificial Intelligence-based approaches from using just uni-modal information to multi-modality for detection and how such paradigm shift facilitates the efficacy of detection, consistent with clinical observations. We conclude that interpretable AI-based predictions and ability to handle class imbalance should be considered priority.