Physical Sciences and Mathematics Commons^™

Population Growth Models: Relationship Between Sustainable Fishing And Making A Profit, James Sandefur

CODEE Journal

In this paper, we develop differential equations that model the sustainable harvesting of species having different characteristics. Specifically, we assume the species satisfies one of two different types of density dependence. From these equations, we consider maximizing sustainable harvests. We then introduce a cost function for fishing and study how maximizing profit affects the harvesting strategy. We finally introduce the concept of open access which helps explain the collapse of many fish stocks.

The equations studied involve relatively simple rational and exponential functions. We analyze the differential equations using phase-line analysis as well as graphing approximate solutions using Euler's method, …

Prediction Of Giant Tunneling Magnetoresistance In Ruo2/Tio2/Ruo2 (110) Antiferromagnetic Tunnel Junctions, Yuan-Yuan Jiang, Zi-An Wang, Kartik Samanta, Shu-Hui Zhang, Rui-Chun Xiao, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal, Ding-Fu Shao

Department of Physics and Astronomy: Faculty Publications

Using first-principles quantum-transport calculations, we investigate spin-dependent electronic and transport properties of antiferromagnetic tunnel junctions (AFMTJs) that consist of (110)-oriented antiferromagnetic (AFM) metal RuO₂ electrodes and an insulating TiO₂ tunneling barrier. We predict the emergence of a giant tunneling magnetoresistance (TMR) effect in a wide energy window, a series of barrier layer thicknesses, and different interface terminations, indicating the robustness of this effect. We show that the predicted TMR cannot be explained in terms of the global transport spin-polarization of RuO₂ (110) but is well understood based on matching the momentum-dependent spin-polarized conduction channels of the two …

Editor's Note, Padraig O'Malley, Adanna C. Kalejaye

New England Journal of Public Policy

To coincide with COP28 in Dubai, this issue of the New England Journal of Public Policy published a series of articles on climate warming.

Data From: Root Distributions Predict Shrub-Steppe Responses To Precipitation Intensity, Andrew Kulmatiski, Karen H. Beard

Browse all Datasets

Precipitation events are becoming more intense around the world, changing the way water moves through soils and plants. Plant rooting strategies that sustain water uptake under these conditions are likely to become more abundant (e.g., shrub encroachment). Yet, it remains difficult to predict species responses to climate change because we typically do not know where active roots are located or how much water they absorb. Here, we applied a water tracer experiment to describe forb, grass, and shrub root distributions. These measurements were made in 8 m by 8 m field shelters with low or high precipitation intensity. We used …

Results Of Cop27 And Expectations For Cop28, Cecilia Kinuthia-Njenga, Fareed Yasseen

New England Journal of Public Policy

Since 1995, government representatives from around the world have gathered nearly every year for the United Nations Conference of the Parties (COP) to advance work on multilateral agreements and to provide a way forward in tackling the significant challenges of climate change. The last of these conferences took place on November 6–20, 2022, in Sharm el-Sheikh, Egypt.

COP27 brought together more than 35,000 people from across the globe to deliberate on important actions for addressing the climate. Hailed as the “African COP” and “Implementation COP,” it raised expectations that decisions from previous conferences, reflecting the needs and priorities of the …

The Perfect Is The Enemy Of The Good: Carbon Credits And Funding For Decarbonization In Developing Countries, Andrew A. Bernstein

New England Journal of Public Policy

Carbon credits issued in the voluntary carbon market are an important source of funding for projects in developing countries designed to reduce greenhouse gas emissions, such as forest preservation and renewable energy. Beyond their potential to provide billions of dollars of private sector financing for decarbonization, carbon credits can generate economic opportunity, employment, and biodiversity. But they are controversial, mainly (but not only) because it is difficult to confirm and to quantify their emissions benefits. This article argues that policymakers should nonetheless support voluntary carbon market growth, so long as companies use carbon credits to mitigate emissions they cannot avoid …

Joint Global Responsibility Fund For Climate, Conservation, And Communities: A Proposed Innovative Tax-Based Funding Mechanism, Tamar Ron

New England Journal of Public Policy

Nature-based solutions address biodiversity loss, climate change, and societal challenges at the local, national, regional, and global levels. The costs of their conservation, however, are mostly local and national in nature. Confronting the rolling dual crisis of biodiversity loss and climate change requires us to recognize nature’s intrinsic value. Moreover, we must find practical ways for their monetary valuation to be channeled as payment for the services of conservation custodians. It is suggested here to translate the value of natural assets and the understanding of the local costs and global benefits of their conservation, into an innovative and ambitious funding …

The How And Why Of Visual Practice At Un Climate Negotiations, Stéphanie Heckman

New England Journal of Public Policy

In this article Stéphanie Heckman examines the process and outcomes of her graphic recording work and other forms of visual practice in the context of UN climate negotiations, reflecting on three years of collaboration with the UN Climate Change Secretariat, particularly during the eighteen-month Global Stocktake process. After a review of the history and science behind visual storytelling, she analyses one of the graphic recordings made for the third meeting of the Technical Dialogue of the Global Stocktake through the lens of Kelvy Bird’s ‘Levels of Scribing’ model. Drawing on comments from delegates at COP27 in Sharm el-Sheikh, Egypt and …

Solar Radiation Modification Governance In The Context Of Temperature Overshoot, Janos Pasztor

New England Journal of Public Policy

As the climate crisis escalates, governments—and recently even those in the wealthier countries in the Global North—are struggling to manage the impacts we are experiencing around the world in frightening abundance, including record-setting temperatures, fires, floods, and glacial and ice melt. Behind closed doors, policymakers are concerned as they contemplate the increasing likelihood, even under the most ambitious emission reduction pathways, that the world will overshoot the goal agreed upon in the Paris Agreement to limit global average temperature rise to 1.5oC beyond pre-industrial levels.

It is in this “overshoot context” that interest is growing in an emerging, potentially supplementary …

Cop27 And The New Rise Of The Global South, Janice Golding

New England Journal of Public Policy

Developing countries require direct and indirect financial and non-financial assistance to address the climate crisis. The COP27 announcement of a new Loss and Damage Fund as well the unveiling of the Bridgetown Initiative collectively hold substantial promise to alter the course of climate multilateralism. The outcome of COP27 has presented unprecedented opportunities for the Global South to build global solidarity for climate justice, but the path ahead will not be easy. Materialization of support to developing countries may be, at best, not sustainable, or at worst, unforeseeable without consistent application of principles and values enshrined in historic, moral accountability for …

The Role Of Carbon Management Technologies In Meeting Net Zero, Ali Al-Saffar

New England Journal of Public Policy

The pathway toward implementing the changes necessary in the energy sector to keep global temperature rises from breaking through catastrophic barriers is narrow and tenuous and will require a range of zero- and low-carbon technologies to be dispatched at a speed and scale that is virtually unprecedented. Decarbonization through renewables, matched with the more efficient use of energy in the end-use sectors will play a large part. But there is growing realization that there will be residual fossil fuel use long into the future, and that the emissions from the burning of these fossil fuels in power plants and factories …

The Gulf: An Appeal For More Coordinated Action On Climate Change, Fareed Yasseen

New England Journal of Public Policy

This article seeks to provide the rationale behind Iraqi Prime Minister Al-Sudani’s call at the United Nations for the formation of a negotiating group within the United Nations Framework Convention on Climate Change process that brings together all member states of the Gulf Cooperation Council, Iraq, and Iran. This article argues that these countries would benefit doubly from such an arrangement, because it would help them better address the direct effects of climate change, on the one hand, and to better address the effects of the measures taken to address climate change, which will affect them as fossil fuel producers, …

A Systematic Collection Of Medical Image Datasets For Deep Learning, Johann Li, Guangming Zhu, Cong Hua, Mingtao Feng, Basheer Bennamoun, Ping Li, Xiaoyuan Lu, Juan Song, Peiyi Shen, Xu Xu, Lin Mei, Liang Zhang, Syed A. A. Shah, Mohammed Bennamoun

Research outputs 2022 to 2026

The astounding success made by artificial intelligence in healthcare and other fields proves that it can achieve human-like performance. However, success always comes with challenges. Deep learning algorithms are data dependent and require large datasets for training. Many junior researchers face a lack of data for a variety of reasons. Medical image acquisition, annotation, and analysis are costly, and their usage is constrained by ethical restrictions. They also require several other resources, such as professional equipment and expertise. That makes it difficult for novice and non-medical researchers to have access to medical data. Thus, as comprehensively as possible, this article …

The Impacts Of The Covid-19 Pandemic On Mental Health Across Different Genders And Sexualities, Jiale Zhu, Jonas Katona

Undergraduate Research Journal for the Human Sciences

Current studies report an increase in psychological distress as a result of the COVID-19 pandemic. This study is interested in examining mental health disparities and how the COVID-19 pandemic has disproportionately impacted marginalized groups—and more specifically, those identified by sex, gender, and sexuality—compared with the general population. This study also considers the effects and ramifications of different policy measures taken during the course of the pandemic. We perform exploratory data modeling and analysis on several important and publicly available datasets taken during the pandemic on mental health and COVID-19 infection data across various identity groups to look for significant disparities, …

Characteristics And Genetic Mechanism Of Low Sulfate In High-Salt Groundwater Of Permian Sandstone In Fudong Mining Area, Huainan, Jiang Chunlu, Huang Wendi, Fu Xianjie, Zheng Liugen, Cheng Shigui, Shan Chonglei

Coal Geology & Exploration

Hydrogeochemistry research of groundwater in coal mining areas is of great significance to the prevention and control of mine water and the comprehensive utilization of water resources. In terms of the low surfate of Permian sandstone water in Fudong mining area, Anhui Huainan Coalfield, the hydrochemical characteristics, water-rock interaction and low sulfate genesis of sandstone water were studied through water sampling and test by multivariate statistical method, in combination with the hydrogeological condition analysis and the sulfur and oxygen isotope technology. The results show that the Permian sandstone water in the study area is weakly alkaline, with an average TDS …

Detection Of Small Objects In Open-Pit Coal Mine Stopes Using Uav Remote Sensing Images, Liu Mingrui, Che Ben, Dong Hongbo, Zhu Ruoli

Coal Geology & Exploration

Open-pit coal mine stopes witness frequent vehicle accidents due to their complex terrains. Therefore, accurately positioning vehicles in the stopes is critical to safe coal mining. To overcome the inaccurate positioning of small targets in the mining areas using Unmanned aerial vehicle (UAV) remote sensing images, this study proposed an improved YOLOv7 model for object detection. First, to expedite the reasoning of the YOLOv7 network, the ELAN module in the original YOLOv7 model was improved by introducing partial convolution. Based on this, the eSE channel attention mechanism was combined to form the PConv-eSE convolution attention module. The purpose is to …

A Method For Evaluating Aquiclude Stability In The Water Conservation-Based Mining Of Shallowly Buried Coal Seams In Ecologically Vulnerable Areas In Northwest China, Li Heng, He Tao, Guo Bin

Coal Geology & Exploration

Water conservation and coal mining are both critical to Northwest China. Water conservation-based coal mining is an important technology for the coordinated development of coal and water resources in this region. In this technology, the evaluation of aquiclude stability is critical. Due to the shallow depth of coal seams, intense topographic cutting, and complex changes in near-surface aquifers in the ecologically vulnerable areas in Northwest China, there exist large errors between traditional methods for aquiclude evaluation and the actual hydrological observations in these areas. To address this challenge, this study develops using the 3D geological modelling combined with numerical simulation …

Obstacle-Avoidance Trajectory Planning Of Mine Drilling Robot During Drill Pipe Loading And Unloading, Yao Yafeng, Yao Ningping, Peng Tao, Liang Chunmiao, Peng Guangyu

Coal Geology & Exploration

The position of drill pipe loading and unloading by mine drilling robot will change with the attitude adjustment of the host machine, and obstacles are present in the loading and unloading path of drill pipe. Therefore, there is a problem of obstacle-avoidance trajectory planning with variable targets in the loading and unloading of drill pipe. For this reason, the DH parameter table was created according to the performance parameters of the explosion-proof 6-DOF manipulator, and the function relation of the change in loading and unloading position of drill pipe before and after the attitude adjustment of the 3-DOF host machine …

Intelligent Optimization Method For Tunnel Rotary Drilling Based On Drill String Status Estimation, Yao Ningping, Wei Hongchao, Zhang Jinbao, Lu Chengda, Li Hao, Yao Yafeng, Ke Yougang, Zhang Youzhen

Coal Geology & Exploration

To address the issue in existing research where it is difficult to obtain bottom-hole drilling parameters while drilling, and to overcome the problem of low accuracy and insufficient improvement when optimizing rotary drilling operational parameters using only borehole data, an intelligent optimization method for near-horizontal tunnel rotary drilling based on drill string status is proposed. This involves constructing an in-hole state observer to estimate bottom-hole drilling parameter information. Firstly, the characteristics of rotary drilling in underground coal mine tunnels are analyzed, considering the constraints of actual drilling, and an optimization target evaluation method for mechanical drilling speed and drill bit …

Table Of Contents, The Editors

Coal Geology & Exploration

No abstract provided.

Stress Field Of High-Temperature Wellbore Under Spray Cooling For Underground Coal Gasification, Tang Yang, Xie Na, Xiong Haoyu, He Yin, Huang Shunxiao

Coal Geology & Exploration

As a supplement to traditional physical coal mining technology, underground coal gasification (UCG) is a new generation of chemical coal mining technology. During the gasification, the wellbore of UCG production wells is subjected to the combined action of high temperature and internal pressure loads. Targeting the structural characteristics of the wellbore of UCG production wells, this study, based on the heat transfer theory, established a calculation model for the transient temperature of the wellbore under the cooling through annular spray water injection. By combining the wellbore pressure model, as well as the elasticity theory and the wall cylinder theory, this …

Micp Restoration Law Of Coal Mining Induced Ground Fissures And Its Influencing Factors, Li Tao, Gao Ying, Yan Jingwang, Zhang Jiarui, Kou Guigui, Ma Tengfei, Mei Aoran

Coal Geology & Exploration

The coal mining induced ground fissures in the loess covered area of northwest China cause shallow groundwater resource leakage and soil instability. Therefore, the experimental study was conducted on Microbial Induced Carbonate Precipitation (MICP) restoration of coal mining induced ground fissures in the loess covered area. Specifically, the characteristics of mining induced ground fissures were observed and their development characteristics were revealed based on Ningtiaota Coal Mine in northern Shaanxi. The coal mining induced ground fissures in loess were classified with consideration to the observed mine pressure. Based on the classification and characteristics of coal mining induced ground fractures, the …

On-Line Compensation For Geomagnetic Error While Drilling Based On Magnetic Inertial Slime Mould Algorithm, Yang Jinxian, Cai Jipeng

Coal Geology & Exploration

In response to the serious distortion of the azimuth angle of the drilling tool caused by the large measurement error of strap-down micro-electro-mechanical-system (MEMS) magnetometer on the drilling tool in the measurement-while-drilling (MWD) environment, an online compensation method for the geomagnetic error of the drilling tool based on the magnetic-inertial slime mould algorithm (MISMA) was proposed. Firstly, the geomagnetic measurement error compensation model of the drilling tool was established through the analysis on the output error of the magnetometer, and the magnetometer error parameters were sorted into solution vectors. Then, the objective function of the ideal magnetic output data, the …

Numerical Simulations Of Enhancing Permeability And Gas Extraction Of Thick Coal Seams Through Static Fracturing, Wang Xinfeng, Liu Wengang, Wang Long, Wei Youyu, Zhang Qiao

Coal Geology & Exploration

This study seeks to improve the underground operation efficiency and optimize the borehole arrangement parameters for static fracturing of coal seams. To this end, this study conducted tests in the belt roadway of the No. 12316 fully mechanized mining face in the Wangjialing Coal Mine, China Coal Huajin Group. By combining the equations for coal seams’ deformation and failure, gas diffusion and seepage, and coal seams’ permeability evolution, this study constructed a model of the damage and permeability evolution of coal seams. Based on the numerical simulations of the process of static fracturing and permeability enhancement of coals, as well …

Genetic Type And Gas-Generating Potential Of Coalbed Methane In The Bayanhua Sag, Erlian Basin, Meng Qin, Li Ling, Li Jie, Tian Wenguang, Lin Haitao, Li Heng

Coal Geology & Exploration

The Bayanhua Sag in the Erlian Basin is a critical experimental area for coalbed methane (CBM) development from low-rank coals in Inner Mongolia. However, the relatively low exploration level and the limited understanding of the CBM origin in the sag restrict the CBM exploration and development to some extent. This study tested the gas components, stable isotopes and hydrochemistry of the gas and water samples from CBM wells in the Bayanhua Sag. It also conducted radioisotopic dating for these samples. By combining the classic charts for the identification of natural gas origin, this study clarified the gas origins, further analyzed …

Vertical Variability Of Hydrogeological Characteristics Of Luohe Formation By Double Packer System Pumping Test, Li Chaofeng, Liu Yexian, Zhang Jinkui, Ren Dengjun, Hou Tao, Liu Zengping, Xu Xinqi, Ma Ji, Wang Qingzhen, Duan Xiliang, Xing Jiebo, Li Yang

Coal Geology & Exploration

To investigate the hydrogeological conditions of the thick Luohe Formation in Ordos Basin and quantitatively evaluate vertical variation characteristics of its aquifer’ s water-rich, proposes the method of using the coefficient of transmissibility to evaluate the water-rich of the aquifer, and give the seven level classification standard of water-rich by the method of determining coefficient of transmissibility. The double-packer system was used to carry out the pumping tests of 10 vertical sections of fixed thickness of the Luohe Formation in the DJ1 and DJ2 boreholes in the Gaojiabao mine field, shaanxi, and the hydrogeological parameters were calculated. Using the comprehensive …

Dynamic Prediction Method Of Tunnel Water Inflow Based On Detailed Depiction Of Complex Geological Bodies, Du Yajun, Li Qingbo, Wan Weifeng, Yang Fengwei, Li Yazhe, Qian Hui

Coal Geology & Exploration

It is a challenge to accurately characterize the irregular geological bodies and underground structures such as inclined faults and inclined tunnels during the numerical simulation of tunnel water inflow prediction, and the prediction generally assumes that the tunnel excavation is completed instantaneously without considering the construction progress. A dynamic prediction method for tunnel water inflow based on precise characterization of complex geometric bodies was proposed by addressing the non-self-intersection and watertight issues required in the coupling process of three-dimensional (3D) geological models and 3D groundwater numerical models. Specifically, a sealed boundary interface of inclined tunnels, shafts, inclined faults and irregular …

A Simulation Study On The Suspension And Transport Patterns Of Proppants In Long Distance Pipelines For Integrated Well And Ground Fracturing, Li Haozhe, Jiang Zaibing, Sun Siqing, Zhu Chuanyong, Fan Yao, Guo Yong, Cheng Bin

Coal Geology & Exploration

Integrated well and ground fracturing is a developmental trend for the staged fracturing of underground long boreholes in coal mines. Using the integrated fracturing technology, the fracturing fluids, after being pressurized using a ground fracturing pump, enter long boreholes in underground coal mines through ground penetrating wells and long distance pipelines, aiming to achieve fracturing with high injection rates of fracturing fluids. The suspension and transport patterns of proppants in long distance pipelines hold critical significance for optimizing parameters related to proppant adding and avoiding sand plugging in pipelines. This study evaluated the rheological properties and proppant carrying capacity of …

Numerical Simulations Of The Effects Of Bedding Planes On Hydraulic Fracture Propagation Law In Oil Shale, Li Yanwei, Zhu Chaofan, Zeng Yijian, Shui Haoche, Fan Cunhan, Guo Wei

Coal Geology & Exploration

Hydraulic fracturing serves as a major technical means for the exploitation of oil shale reservoirs presently, and the hydraulic fracture morphology in oil shales is primarily affected by differences in the characteristics of bedding planes. However, current studies mostly focus on the influence of the developmental degree of bedding planes on fracture propagation, overlooking the effects of the bedding plane thickness itself on hydraulic fracture propagation. This study delves into the oil shale in the Xunyi area, Ordos Basin. Based on the theory of linear elastic fracture mechanics, this study developed a stress-damage-seepage model of hydraulic fracture propagation. Using the …

Evaluation Of Water Quality And Identification Of Pollution Factors In Mining Subsidence Area With High Phreatic Water Level, Hu Lin, Chen Yongchun, Xu Yanfei, Li Bing, Wang Jin, An Shikai, Chen Chen, Sun Hongjie, Miao Wei

Coal Geology & Exploration

Huainan mining area is characterized by a high phreatic water level, as well as a wide range and large area of coal mining subsidence areas, with the water quality monitoring data missing and prominent water environment. Therefore, the evaluation of water quality monitoring and identification of pollution factors in large subsidence area is of great significance to regional water environmental governance. Specifically, the water quality of the subsidence area was evaluated with the Nemerow pollution index method by testing the water samples collected from 175 sampling points in the study area. Meanwhile, the eutrophication state of water bodies was evaluated …