ALBERT

Description: In the study of solar-terrestrial relationships, magnetic storms and solar activity play important roles. In this paper, the intense magnetic storms in company with solar proton events occurred in October and November 2003, January 2005, December 2006, January and March 2012 have been considered. The variation of the odd nitrogen (NOy) oxides and ozone in the stratospheric layer is investigated by the effects of energetic particle precipitation. Anomaly percentage of the odd nitrogen (NOy) oxides and ozone are calculated separately for the Southern and the Northern hemispheres and geographic latitude from 60 to 80 degrees. The analyzed results of the observational data showed that the intense magnetic storms, which consist of more than 500 (particles/cm2 s sr) solar energetic proton (E〉10MeV), gave rise to the increase of the odd nitrogen (NOy) oxides in the stratosphere, from level 1 mb to 200 mb. Also, the results showed that in November 2003, January 2005, December 2006, January and March 2012 the odd nitrogen (NOy) oxides, which consist of over 500 (particles/cm2 s sr) increased in the Northern hemisphere but decreased a little in the Southern hemisphere . Among the events of the magnetic storms in the autumn and winter seasons, the only event on the October 2003, showed that the odd nitrogen (NOy) oxides increased in the Southern hemisphere. The results showed that the increase in the odd nitrogen (NOy) oxides caused a decrease of ozone in the altitude below the odd nitrogen (NOy) with a delay.

Description: The electrical properties of rock types or channel structures have been the object of intense studies for many years. The main aim of the present work is to show the frequency response of electrical properties of some Granite samples concerning chemical, minor and major composition. This may be used as a fingerprint for the characterization of some Granite rocks. Electrical measurements on Granite samples (surface, Aswan, Egypt) were measured (100 Hz up to 107 Hz). Differences in samples due to changes in texture lead to different changes in electrical properties. The changes at conductivity and dielectric constant are reflections from the texture within grains. Conductivity and dielectric constant values extend from ~10-8 to 10-4 (S/m) and 24 to 3.5, respectively. With frequency increase, conductivity increases, and dielectric constant decreases (10 kHz), and then it settles down. Differences in electrical properties between samples are small as a direct result of the homogeneity and texture of most samples. There is a high dispersion of dielectric constant for relatively low-frequency values (〈10 kHz) and no dispersion at relatively high frequencies. In conclusion, the dielectric constant decreases due to the shrinkage of energy levels for electrons and the increase of hopping particles between different particles.

Description: A strong earthquake () (34.911° N, 45.959° E, ~19 km depth) occurred on November 12, 2017, at 18:18:17 UTC (LT=UTC+03:30) in Sarpol-e Zahab, Iran. Six different Neural Network (NN) algorithms including Multi-Layer Perceptron (MLP), Recurrent Neural Network (RNN), Gated Recurrent Unit (GRU), Convolutional Neural Network (CNN), Long-Short Term Memory (LSTM) and CNN-LSTM were implemented to survey the four months of GPS Total Electron Content (TEC) measurements during the period of August 01 to November 30, 2017 around the epicenter of the mentioned earthquake. By considering the quiet solar-geomagnetic conditions, every six methods detect anomalous TEC variations nine days prior to the earthquake. Since time-series of TEC variations follow a nonlinear and complex behavior, intelligent algorithms such as NN can be considered as an appropriate tool for modelling and prediction of TEC time-series. Moreover, multi-methods analyses beside the multi precursor’s analyses decrease uncertainty and false alarms and consequently lead to confident anomalies.

Description: Direct current electrical resistivity imaging is provided by measuring the vertical and horizontal electrical potential variations of subsurface structures using surface and borehole records. To recover the resistivity tomograms from the observed data, a non-linear inverse problem is required to be iteratively solved. A 2.5-dimensional forward modeling based on the finite-difference method with rectangular meshes is also formulated. The two-dimensional reconstruction of earth resistivity data is implemented using a smoothness constrained inversion algorithm (i.e. Occam’s method), wherein a Gauss-Newton technique for updating the sensitivity function is proposed. After verifying the accuracy and efficiency of the forward modeling and the sensitivity function calculation, the inversion algorithm is tested on synthetic data from both geometrically simple and complicated bodies and a real data set. A stopping criterion based on the noise level, roughly estimated using the method of reciprocal resistance measurements, is also provided leading to preventing over-or under-interpreted structure during the inversion process. The numerical experiments reveal that the proposed inversion algorithm provides stable inversion results and an acceptable representation of the main features and structure of the models without producing spurious effects. Furthermore, to deal with the reliability of the recovered models, a model sensitivity analysis is implemented using the resolution density distribution. All used formulations and concepts are part of a Matlab source code developed during this study.

Description: یکی از نتایج مهم نظریه گرانش کوانتومی اصلاح قوانین فیزیک در فواصل کوتاه است. مثلا روابط جابجایی مکانیک کوانتومی استاندارد در مقیاس هایی از طول – به نام طول پلانک – تغییر می یابند. البته باید توجه داشت که این تغییرات در انرژی های پایین قابل صرفنظر کردن است و فقط در حد انرژی های بالا همچون جهان اولیه این تصحیحات قابل توجه می شوند. در این راستا اصل عدم قطعیت استاندارد مکانیک کوانتوم با روابط اصلاح شده عدم قطعیت که شامل یک طول کمینه قابل مشاهده از مرتبه پلانک است تغییر می یابند. از طرفی لحظات ابتدای پیدایش عالم که شامل دوره تورم بوده دوره ای است که به دلیل سطح بالای انرژی ، اثرات کوانتومی گرانش در آن قابل توجه و لذا می توان در این دوره به بررسی این اثرات پرداخت. برای این کار می توان ویژگی های دوره تورمی را از روی پارامتر های اولیه عالم همچون افت و خیزهای اولیه تشکیل ساختار عالم و نمایه طیفی مورد بررسی قرار داد. این پژوهش اثرات کوانتومی گرانش را در یک مدل برداری گرانش تعمیم یافته مورد بررسی قرار داده ایم. به این صورت که با استفاده از اصل عدم قطعیت اصلاح شده از طریق هندسه ناجابجایی (که بر اساس اصلاحات گرانش کوانتومی بدست آمده)، دینامیک تورمی جهان اولیه را مورد مطالعه قرار داده و سپس اثرات کوانتومی گرانش ناشی از تعمیم اصل عدم قطعیت را در پارامتر نمایه طیفی را بررسی می کنیم . همچنین چگالی اختلالات اسکالر متاثر از این اثرات مورد محاسبه قرار گرفته است.

Description: با توجّه به اهمیّت پدیده‌ی تغییرات آب‌وهوایی و گرمایش جهانی، آگاهی از رفتار گذشته، حال و آینده‌ی عناصر آب‌وهوایی از اهمیّت شایان توجهّی برخوردار است. در همین راستا، در پژوهش حاضر تلاش می‌شود داده‌های میانگین سالانه‌ی دما در ایستگاه مهرآباد تهران از سال 1330 تا 1394 بررسی شود. بدین منظور و برای شناسای تغییرات زمانی میانگین دمای سالانه، مدل سازی آماری – خانواده‌ی مدل‌های آریما (ARIMA) به کار گرفته شد. برای نیل به این هدف، معنی‌داری آماری مراتب و اجزای مختلف مدل، برای پیش‌بینی وارسی شد. در نهایت دو مدل ARIMA(0,1,1)_{con}، و ARIMA(2,1,0)_{con} به عنوان مدل‌های رقیب انتخاب شدند. معیارهای نهایی نشان دادند که مدلARIMA(0,1,1)_{con} به عنوان مناسب‌ترین مدل برازنده بر دمای سالانه‌ی ایستگاه مهرآباد تهران است. همچنین، آزمون‌های آماری خودهمبستگی، ضریب همبستگی پیرسون، همگنی نرمال استاندارد، وانیومن، انحرافات تجمعی، نقاط عطف، علامت و پورت مانتئو برای وارسی رفتار باقی‌مانده‌های مدل پیش‌بین استفاده شد. علاوه بر این، شیوه‌های ترسیمی برای نرمال بودن باقی‌مانده‌ها، استقلال ، ثابت بودن واریانس بر روی باقی‌مانده‌های مدل ARIMA(0,1,1)_{con}، در راستای بالا بردن اطمینان آماری عدم قطعیّت مدل پیش‌بین انجام شد. یافته‌های حاصل از مدل نشان می‌دهد که به‌طور میانگین هر سال نسبت به سال قبل از خود حدود میزان 038/0 درجه‌ی سلسیوس افزایش دما را تجربه می‌کند. میانگین دمای 16 سالۀ پیش‌بینی به طور میانگین برابر 742/17 درجه‌ی سلسیوس خواهد بود. نتایج آزمون‌ها نیز نشان دادند باقی‌مانده‌های مدل ARIMA(0,1,1)_{con} رفتار تصادفی دارند، که نشان می‌دهد مدل حاصل، برازنده‌ی پیش‌بینی برای سری زمانی میانگین سالانه دما در ایستگاه مهرآباد تهران است.

Description: شناسایی رفتارهای تناوبی و تصادفی سری‌های زمانی پارامترهای توجیه زمین (EOP)، به‌منظور کاربردهای مختلفی همچون تعیین دقیق مدار ماهواره‌ها، نجوم ژئودزی، ناوبری فضایی و همچنین مطالعه‌ی پدیده‌های ژئوفیزیکی مورد نیاز می‌باشد. روش‌های مختلف آنالیز سری‌های زمانی از دیرباز تا کنون مورد بررسی قرار گرفته است. در این تحقیق، بررسی و تعیین فرکانس‌های موجود در پارامترهای توجیه زمین، با استفاده از آنالیز هارمونیک کمترین مربعات یک متغیره و چند متغیره‌‌ی سری‌های زمانی IERS 14 C04، از تاریخ اول ژانویه 1980 تا 31 دسامبر سال 2020 صورت گرفته است. با تشکیل مدل تابعی با استفاده از فرکانس‌های تعیین شده، ضرایب مدل تابعی با استفاده از برآوردگر کمترین‌مربعات برآورد شدند. سپس مدل مناسب اتورگرسیو-میانگین متحرک (ARMA)، متناظر با بردار باقیمانده‌های کمترین‌مربعات حاصل از این مدل تابعی تعیین گردید. در نهایت با استفاده از ضرایب برآورد شده‌ی مدل تابعی و مدل ARMA، پارامترهای توجیه زمین برای 20 روز اول سال 2021 پیش‌بینی شدند و دقت روش ارائه شده مورد ارزیابی قرار گرفت. نتایج این تحقیق با دو روش یادگیری عمیق مقیاسه گردید و نتایج نشان داد دقت بهتری نسبت به آن‌ها داراست و رفتارهای تناوبی و تصادفی EOP با دقت بالایی شناسایی شده‌اند. پس از گذشت 10 روز دقت پیش‌بینی برای مولفه‌ی x حدود 9/7 برابر، برای مولفه‌ی y حدود 5/3 برابر و برای مولفه‌ی LOD حدود 5/1 برابر بهبود یافت. همچنین با گذشت 20 روز دقت روز دقت پیش‌بینی برای مولفه‌ی x حدود 15/1 برابر ،برای مولفه‌ی y حدود 89/2 برابر و برای مولفه‌ی LOD حدود 18/5 برابر بهبود یافت.

Description: This research is focused on the dolines of Dobrá Voda Karst, which is situated in the Brezovské Karpaty Mts. (north-eastern part of the Malé Karpaty Mts) near the villages of Chtelnica and Dobrá Voda. 263 dolines were identified here and measured in the field, which is presumably the final count. The measured parameters of the dolines were used for morphometric analyses, as well as for finding out the relationships with the geology of the area. The karst is formed in Triassic carbonates of the Považie and Dobrá Voda nappes of the Hronic Unit. Dolines were identified in Neogene basal carbonatic conglomerates (Dobrá Voda Formation) as well. The area of karst rocks is approximately 87.2 km2. Dolines often tend to be formed in lines with tectonical or lithological predisposition. The most significant lines in the Dobrá Voda Karst are Hlboký Dol, Chtelnické Uhliská, and Cínovec. The origin of dolines can be assumed to the Quaternary Period and related to neotectonics, the development of the relief, and the formation of the river network. This is also confirmed by the trends of the maximum axes of the extension of dolines in the direction N-S, NE-SW and WNW-ESE, which partially correspond to the regional faults. New faults (Hlboký Dol, Cínovec, Bzová) were also identified on the basis of dolines in the lines.

Description: In this paper, a code for 3D forward modeling of electromagnetic low induction number (EM-LIN) data is developed based on the linear integral equations (IE). At first, the code is manipulated for a resistive block immersed in a homogenous background, and the obtained results have RMS errors of 2% comparing with the previously standard published results, which demonstrates the productivity of the 3D forward modeling code. Then, a model composed of two conductive anomalies with different depth ranges and conductivities in a resistive background is considered. IE Forward reposes shows that the shallower block produce larger values in spite of having less conductivity.Since the forward modeling is linear, the productivity of the forward modeling code depends on the efficiency of the forward operator. Furthermore, linear forward operator plays the key role in the linear inversion procedure, therefore, a real data set of a thick dyke in Bloemfontein Nature Reserve region in South Africa is manipulated. Weighted damped minimum length solution is utilized for the inversion procedure and the inverted model is demonstrative of the forward operator efficiency in practical applications.

Description: In recent years, an increase in the frequency of dust storms in the Middle East has been experienced. Identifying the potential sources of dust is essential to manage the hazardous consequences of dust storms. In addition, the relation between dust events and meteorological factors such as wind speed and horizontal visibility in the Middle East is lacking. The relation between dust events and topographical features such as soil texture in the Middle East is also unclear. In this study, dust events in the Middle East were classified based on horizontal visibility and the present weather reports during the period 1996-2015. Frequencies of different types of dust events, including blowing dust, dust in suspension, dust storm and severe dust storm, were estimated. The average concentrations of dust particles in the Middle East were also estimated based on horizontal visibility. Wind speed makes a critical contribution to dust events in the Middle East, thus wind speeds were also analyzed over the regions with relatively high frequency of dust events. In addition, maps of soil texture, elevation of landforms and the vegetation cover percentage, which have been obtained by the Weather Research and Forecasting (WRF) preprocessing system (WPS), were evaluated. The highest frequency of dust events is observed in five domains, which include Sudan, Saudi Arabia, Iraq, the United Arab Emirates (UAE), Afghanistan, Pakistan and Iran. Dust in suspension has the highest frequency among all types of the dust events studied here, particularly in southeastern Iran and central and eastern Iraq. Seasonal variations in dust event activity are directly related to wind speed, such that the frequency of dust events is the highest in June and July when winds are strongest, and lowest in January when winds are weakest. Maximum dust concentrations are observed in Saudi Arabia, Yemen and Iraq. The maximal frequency of dust storms in the Middle East occurs in May, June and July. Due to the differences in soil texture, elevation and vegetation cover, the dust emission in the Middle East is characterized by significant spatial heterogeneity. Our numerical analysis shows that sources of dust in the Middle East are mostly topographical lows with heights below 400 m, including sources in Sudan, northeastern and eastern Saudi Arabia, Iraq and Pakistan. Nevertheless, in the southwestern Arabian Peninsula, the height of sources of dust reaches to approximately 1200-2400 m. The upper surface texture of soil in region A (northeastern Sudan) is loam and sandy loam, in region B (Yemen and the southwestern Arabian Peninsula) is loamy sand and loam, in region C (northeastern Saudi Arabia, eastern Iraq and western Iran) is clay loam and loam, in region D (the UAE) is sand, sandy loam and loam, and in region E (Afghanistan, Pakistan and southeastern Iran) is loam clay and loam. The upper surface texture of soil in areas with the highest dust frequency is sandy loam and clay loam. The spatial distributions of the vegetation cover percentage show a sharp decline (below 1%) in Sudan, Saudi Arabia, Iraq, Central and Southern Iran and Pakistan.

Description: 〈p〉The invasion of Ukraine by Russian forces has led to sharp rises in gas prices in Europe and around the world with real concerns about the possible curtailment of gas flows from Russia to Europe. Pipeline imports from Russia began falling in the last quarter of 2021 and declined even further in January and most […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/ukraine-invasion-what-this-means-for-the-european-gas-markets/"〉Ukraine Invasion: What This Means for the European Gas Market〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: عدم‌توازن و به دنبال آن شکل‌گیری امواج گرانی- لختی به‌عنوان یکی از عوامل شناخته‌شده در وقوع تلاطم هوای صاف (CAT)، در وردسپهر زبرین شناخته می‌شوند. در این پژوهش ابتدا امواج کژفشار با استفاده از مدل WRF به صورت آرمانی در یک کانال با ابعاد 4000، 10000 و 22 کیلومتر به‌ترتیب در راستاهای مداری، نصف‌النهاری و قائم بر روی صفحهf با تفکیک افقی (قائم) برابر با 25 (25/0) کیلومتر برای 15 روز شبیه‌سازی شد. در ادامه، با کاربست روش تجزیه موج-تاوه، بخش نامتوازن شارش تعیین و برای محاسبه دامنه و دامنه بی‌بعد امواج گرانی-لختی مورد استفاده قرار گرفت. سپس مقادیر دامنه بی‌بعد امواج گرانی-لختی، برمبنای نظریه عدم‌توازن خودبه‌خودی لایت‌هیل- فورد، روش ناکس و همکاران (2008) (KMW)‌ نیز محاسبه شد و برای بررسی تلاطم و شدت آن، اتلاف انرژی جنبشی تلاطمی و آهنگ اتلاف پیچکی (EDR) با استفاده از مقادیر هر دو دامنه محاسبه شدند. نتایج توزیع EDR با استفاده از دامنه بی‌بعد روش تجزیه موج-تاوه نشان داد که در تمام محدوده اطراف جریان‌ جتی تلاطم متوسط وجود دارد و بیشینه این مقادیر، در نواحی پایین هسته و خروجی جریان‌ جتی قرار می‌گیرد که منطبق بر محل فعالیت امواج گرانی- لختی و مطالعات پیشین CAT نیز است. همین‌طور نتایج توزیع EDR با استفاده از دامنه بی‌بعد روش KMW تلاطم‌های شدید را در مناطق کوچکی بر روی هسته جت و در ناحیه ورودی جریان جتی نشان می‌دهد و بر‌خلاف روش تجزیه موج- تاوه در بیشتر مناطق، تلاطمی پیش‌بینی‌ نمی‌شود که این امر می‌تواند به اختلاف دو روش در محاسبه دامنه امواج مربوط باشد.

Description: با توجه به نیاز اکتشاف منابع کم عیار نظیر پورفیری‎ها به دلیل کاهش ذخایر کانه‎ های معدنی پرعیار سطحی، امروزه پی‎جویی‎های ژئوفیزیکی مورد توجه بیشتری قرار گرفته‎اند. وجودکانی‎هایی با خودپذیری مغناطیسی و رسانایی الکتریکی بالا در محدوده زون پتاسیک کانسارهای مزبور، استفاده از روش‎های مغناطیس‌سنجی، مقاومت ویژه و پلاریزاسیون القایی را به منظور تخمین عمق و شکل کانسارهای مزبور امکان پذیر می‎سازد. در تحقیق حاضر داده‎های یاد شده در محدوده کانسار پورفیری مس و طلای دالی جنوبی مورد مطالعه مجدد قرار گرفته‎اند تا با انجام پردازش‎ها و مدل‎سازی‎های جدید، نتایج مطالعات قبلی را بهبود بخشیده و ارتباط کانی‎زایی با مدل‎های ژئوفیزیکی جدید مشخص گردد. در این بررسی برای اولین بار با انجام مدل‌سازی وارون سه بعدی داده‌های پردازش‎شده مغناطیس‌سنجی در این منطقه و تحلیل خطای آن، مقاطعی از خودپذیری مغناطیسی در جهت آزیموت گمانه‌های موجود در منطقه به همراه نتایج عیار طلا و مس به دست آمده از آنالیز ژئوشیمیایی گمانه‎ها ارائه شد. همچنین نتایج مدل‌سازی وارون دو بعدی داده‌های مقاومت ویژه و پلاریزاسیون القایی در راستای سه پروفیل با خطای مناسب نیز ضمن سازگاری با نتایج مطالعات قبلی، با خودپذیری مغناطیسی تخمین زده شده در راستای یک پروفیل IP/Res مقایسه گردید. مقایسه مقاطع و صحت سنجی آن‌ها با عیار مس و طلای موجود در طول گمانه‌ها نشان می‎دهد که مناطق مشکوک به کانی‌سازی، در ارتباط با خودپذیری مغناطیسی و شارژ پذیری بالا و مقاومت ویژه کم بوده و با توجه به مدل‌مغناطیسی، حداکثر کانی‌سازی در حاشیه توده با خودپذیری مغناطیسی بالا مشاهده می‌شوند.

Description: این مطالعه به مقایسه کارایی دو روش کولوکیشن کمترین مربعات و انتگرال پواسن در انتقال فروسوی داده های گرانی هوابرد با استفاده از داده های زمینی در منطقه کلرادو امریکا اختصاص دارد. روش کولوکیشن نیاز به داده های با خواص آماری مستقل از مکان و جهت دارد. لذا اثر طول موجهای بلند با استفاده از مدل ژئوپتانسیل و اثر طول موج های کوتاه توپوگرافی از روی داده ها برداشته شد. حذف اثر طول موجهای کوتاه مدل از مدل پتانسیل پوسته dV_ELL_Earth2014_5480 از درجه/مرتبه 5480/5480 انجام شد. نتایج عددی با داده های شبیه سازی شده در ارتفاع پرواز و سطح زمین نشان از برتری روش پواسن نسبت به کولوکیشن در انتقال فروسوی داده های هوایی دارد. اختلاف بین نتایج عددی روشهای کولوکیشن و انتگرال پواسن برابر 2 میلی گال است. این مقدار در سطح نویز داده ها است. همچنین انحراف معیار اختلاف بین نتایج هر دو روش با داده های زمینی حدود 8 میلی گال است. همچنین هر دو روش وجود یک بایاس به اندازه 2 میلی گال در داده های هوابرد را نشان می دهند. با توجه به وجود همین مقدار بایاس در داده های زمینی نمی توان این مقدار بایاس را برای داده های هوابرد کلرادو نسبت داد.

Description: Hexlant explores the current state and future of decentralized autonomous organizations.〈div class="enclosure"〉〈/div〉

Description: Direct legal regulation is not the most efficient primary tool for regulating DEX protocols. Code is. When DEX protocol’s architecture falls short is when the law should step in to supplement code in order to shape behavior to ensure maximum public value for minimum public cost.〈div class="enclosure"〉〈/div〉

Description: The use of distributed ledger technology-based tools and smart contracts for customs compliance purposes subjects the idea of a “declarant” or “declaration” to potential re-characterization.〈div class="enclosure"〉〈/div〉

Description: The AsicBoost patent controversy led to the creation of the Blockchain Defensive Patent License and may also have influenced the creation of the Cryptocurrency Open Patent Alliance.〈div class="enclosure"〉〈/div〉

Description: آنامولی سطح دریا به عنوان کمیتی که بیان‌کننده اختلاف ارتفاع سطح‌لحظه‌ای آب با مقدار متوسط سطح‌آب در یک بازه زمانی می‌باشد در مطالعه وضعیت سطح آب مناطق مختلف دارای اهمیت چشمگیری می‌باشد. منطقه آبی دریاچه خزر به عنوان یکی از دو منبع مهم آبی برای کشور ایران از اهمیتی استراتژیک برخوردار است. بدین منظور در این پژوهش با استفاده از داده‌های گذر 92 مأموریت‌های ارتفاع‌سنجی‌ماهواره‌ای؛ عبوری از منطقه آبی خزر به مشاهده تغییرات کمیت آنامولی سطح دریا در این منطقه از سال 1993 تاکنون پرداخته شده است. سپس این کمیت با استفاده از روش تجزیه به مودهای ذاتی به عنوان روشی کارا در جداسازی فرکانس های تشکیل‌دهنده یک سیگنال مورد آنالیز قرار گرفته است و سپس با استفاده از شبکه عصبی توابع پایه شعاعی یک شبکه به منظور پیش‌بینی آنامولی سطح دریا ایجاد گردیده است. 9 فرکانس غالب به همراه یک ترند نتیچه تجزیه سیگنال مدنظر در این پژوهش می باشد که در نهایت منجر به پارمترهای مجذور میانگین خطا به میزان 0/029 متر و 0/034متر به همراه ضریب همبستگی 0/99 و 0/97 به ترتیب در دو مرحله آموزش و تست شبکه عصبی می‌شود.

Description: حفاظت قطعات الکترونیکی در برابر پرتوهای فضایی یکی از مهم‌ترین الزامات اولیه در طراحی و ساخت ماهواره‌ها می-باشد. در این کار با محاسبه دز ناشی از پرتوهای فضایی در ماده سیلیکونی با استفاده از کد مونت کارلوی MCNPX به ارزیابی تاثیر سازه‌های مختلف در حفاظ سازی پرتوهای فضایی پرداخته شده است. حفاظ پرتویی چند لایه متشکل از آلومینیوم، کربن و پلی‌اتیلن طراحی شد و عملکرد آن با حفاظ‌هایی از جنس آلومینیوم و پلی‌اتیلن برای بازه‌های دز متفاوت بررسی شد. همچنین سه بازه دز پرتویی که برای اکثر قطعات تجاری بصورت ریسک کارکردی تعریف می‌شود در نظر گرفته شد. نتایج نشان می دهد که با جایگزینی حفاظ چند لایه به جای حفاظ مرسوم آلومینیومی در بازه های دز مشخص، در بیشترین حالت 12/22% کاهش وزن حاصل خواهد شد. علاوه برآن، در صورت عدم الزام به استفاده از جعبه-های آلومینیومی جهت قرارگیری قطعات الکترونیکی داخل ماهواره، استفاده از حفاظ پلی‌اتیلنی از لحاظ بودجه وزنی در حالت خطر بالا با 65/17%، خطر متوسط 16/13% و خطر کم با 23/19% اختلاف نسبت به حفاظ آلومینیومی مقرون به‌صرفه می‌باشد.

Description: Different learning methods have been used to recognize seismic facies and reservoir characterization using seismic attributes. One of the significant issues in automatic facies analysis is to relate the seismic data to facies properties using the well data. According to previous studies, the role of attributes is more significant than the learning method for automatic classification. The proposed method uses supervised selection of seismic attributes for automatic facies analysis.Extended Elastic Impedances (EEI) at different angles as seismic attributes are being increasingly utilized in both seismic facies analysis and reservoir characterization. They are representative of elastic parameters of rocks appropriately. In the presented method, proper EEI seismic attributes are selected after a feasibility study using petro-physical logs, and EEI template analysis of the well data. Adaptive Neuro-Fuzzy Inference System (ANFIS) is applied to the fuzzy coded data of the well facies to train an automatic model to predict facies from the seismic data. Subsequently, the same particular EEI attributes are prepared. The EEI attributes from the seismic data are inputs for the trained ANIFIS model to perform seismic facies analysis. In this method, the seismic facies and the well facies are compatible. Only one well data can be sufficient for the well analysis stage and well facies clustering.The proposed method is applied on 3D prestack seismic data located in Abadan plain to discriminate hydrocarbon interval of Sarvak Formation. The results reveal that the supervised selection of attributes and fuzzy concepts present remarkable ability in dealing with imprecise seismic facies analysis and reservoir characterization.

Description: The radon transform has a wide application in seismic processing for each project in different areas. Multiple attenuation is mostly summarized in the use of radon analysis in practice, especially in marine data processing. The definition of mute function is the major challenge in parabolic radon transform. In this paper, a method for segmentation of the radon transform by fuzzy inference system is introduced to separate energy parts in the radon domain. We applied a fuzzy inference system based on the property of energy distribution and its attribute in the radon domain. The result of clustering is the partitioning of the radon domain in three major classes: 1- random noise, 2- multiple, and 3- primary and multiple. The result of applying the new method on real data has shown the applicability of the new method for separation of multiple class from other classes that can assist the processor to define the mute function in the absence of other events in the radon domain.

Description: این پژوهش با هدف درستی سنجی و پیش بینی دهه‌ای دمای ماهانه ایران با استفاده از برونداد پروژه پیش بینی اقلیمی دهه ای (DCPP) که در پروژه مقایسه مدل‌های جفت شده فاز ششم (CMIP6) مشارکت داده شده است، انجام شد. به این منظور از دو گروه داده شامل دمای 42 ایستگاه همدید و برونداد دو مدل BCC-CSM2-MR و MPI-ESM1-2-HR با تفکیک افقی 100 کیلومتر برای دوره گذشته نگر(2019-1980) و دوره پیش‌بینی (2028-2021) استفاده شد. برای درستی سنجی‌ مدل‌ها از سنجه های آماری RMSE ، MBE و PCC و نمودار تیلور استفاده گردید. نتایج درستی سنجی نشان دهنده کارایی بهتر مدل MPI-ESM1-2-HR نسبت به مدل BCC-CSM2-MR در ایران می‌باشد. در مقابل مدل BCC-CSM2-MR به خصوص در سواحل شمالی و جنوبی کشور با خطای قابل توجهی همراه بوده و صرفاً در مناطق کوهستانی ایران عملکرد قابل قبولی را نشان داده است. نتایج بررسی دمای ماهانه دوره گذشته‌نگر با استفاده از مدل MPI-ESM1-2-HR نشان داد که این مدل بخوبی الگوهای دمایی کشور را به تصویر می‌کشد. پیش‌بینی دمای ایران برای دوره 2028-2021 نشان داد که بی‌هنجاری دما در دهه‌ی‌ آینده در تمامی ماه‌های سال مثبت و بطور متوسط 0.9 درجه‌سلسیوس افزایش می‌یابد. آنچه در این میان بسیار حائز اهمیت است بی‌هنجاری مثبت دمای ماه‌های مارس، آوریل، ژوئن و ژوئیه در تمامی پهنه‌های اقلیمی کشور است. بی‌هنجاری مثبت در این ماه‌ها بیش‌از یک درجه سلسیوس بوده که یک تهدید جدی برای محیط زیست و منابع آب ایران در سال‌های آینده به‌شمار می‌رود.

Description: در مسائل مرتبط با هواشناسی، آبشناسی و کشاورزی دسترسی به پیش‌بینی‌های دقیق دمای کمینه و بیشینه در هر مکانی ضروری است. ازاینرو استفاده از پیش‌بینی‌های با دقت مناسب مدل‌ WRF در تمام نقاط شبکه ضروری است. اما خروجی مدل با خطای سامانمند همراهست. هدف این مطالعه تصحیح خطای پیش‌بینی‌های 24، 48 و 72 ساعته دمای بیشینه و کمینه در نقاط شبکه بر روی ایران است. خطای مدل طی دوره آموزش 5 و 14 روزه، برای نقاطی از شبکه که دارای داده مشاهداتی هستند محاسبه شد. این خطاها در نواحی هم‌اقلیم، با استفاده از روش درون‌یابی کوکریجینگ، در سایر نقاط شبکه برآورد شد. بدین ترتیب پیش‌بینی خام مدل برای نقاط فاقد داده مشاهداتی حفظ، و تنها مقادیر برآورده شده خطا بر روی آنها اعمال می‌شود. دوره آماری 15 ماه، از 1/11/2019 الی 1/2/2021 برای 560 ایستگاه مشاهداتی کشور در نظر گرفته شد. نتایج نشان داد خطای برونداد خام مدل در ماه‌ها، مکان‌ها و نواحی اقلیمی مختلف، توزیع یکنواختی ندارد. RMSE برونداد خام مدل برای کل کشور در پیش‌بینی‌های دمای بیشینه و کمینه به ترتیب تقریباً 6 و 5 درجه سلسیوس است، که بعد از تصحیح، به ترتیب به کمتر از 2 و 4 درجه می‌رسند. تغییر‌پذیری نمره مهارت در تمامی نواحی اقلیمی و ماه‌های مختلف بعد از تصحیح خطا بسیار کاهش یافته و در محدوده صفر تا یک قرار می‌گیرد. روش تصحیح خطای 14 روزه نسبت به روش 5 روزه چندان سبب بهبود نمره مهارت مدل نشد و می‌توان با روش 5 روزه با هزینه محاسباتی کمتر به دقتی مشابه رسید.

Description: گسل دوچاه با ظاهری خمیده و با راستای تقریبی خاوری-باختری و شیب حدود 70 درجه به سمت شمال واقع در پایانه شمال باختری گسل قم- زفره، از ساختارهای جالب توجه در ایران مرکزی می‌باشد. تاکنون پژوهش‌های متعددی به‌ویژه از دیدگاه رسوب‌شناسی و دیرینه‌شناسی در منطقه دوچاه صورت گرفته‌است اما کماکان اطلاعات ساختاری از گسل دوچاه واقع در باختر استان قم (کوه‌های یزدان و دوچاه) بسیار اندک است. در این پژوهش با تمرکز بر اطلاعات هندسی وجنبشی گسل دوچاه و پهنه‌ی دگرریخت شده‌ی اطراف آن در سازندهای قم و قرمزفوقانی به تحلیل تنش دیرینه در این محدوده پرداخته شده است که موقعیت محور یبیشینه تراکمی اصلی (σ1) و محور بیشینه کششی اصلی(σ3) به ترتیب برابر با 05 / 030 و 05 / 285 بدست آمد. تحلیل هندسی و جنبشی ساختاری مرتبط با گسل دوچاه و با توجه به آرایش فضایی محورهای اصلی تنش بیانگر فرانهادگی برش چپگرد بر روی برش راستگرد بویژه در قسمتهای باختری منطقه است که دلیل این امر را میتوان به خمیدگی رو به شمال گسل دو چاه و چرخش ورقه خزر (کاسپین) نسبت داد. آرایش خط‌های گذر تنش بیشینه، نشانگر پیروی آن‌ها از رژیم تنشی کلی حاکم بر پوسته ایران است. پتانسیل حرکتی گسل‌ها (Fault Movement Potential) رابطه نزدیکی با وضعیت تنش زمین‌ساختی حاکم در محدوده آن گسل دارد. با توجه به موقعیت فضایی بین گسل دوچاه و محور تنش بیشه تراکمی (σ1)، پتانسیل حرکتی گسل دوچاه حدود 33/0 برآورد گردید که نشانگر پتانسیل پایین این گسل برای فعالیت و ایجاد زمین‌لرزه‌ است.

Description: This paper investigates the mechanism of the eddy’s formation and their locations in the Caspian Sea using numerical simulations. The HYCOM model is used to simulate the evolutions of eddies. The model ran for 18 years from 1992 to 2009 while river runoff and atmospheric forcing are applied in the model as input files. The model output is appropriately compared to some observation data. The results indicate that one cyclonic eddy in the middle and two cyclonic and anticyclonic eddies in the southern basin of the Caspian Sea are the main eddies in this closed sea. Herein we prepare a comprehensive map to show the exact location of eddies with their important features like scales of them in all months using model simulation outputs. Topographic steering seems to be very important in the formation of mesoscale deep basin size eddies.

Description: روش های پالایش رقمی برای جداسازی اطلاعات مجزا از سیگنال های پیچیده هواشناسی بسیار موثر هستند. هدف از مطالعه حاضر طراحی پالایه مناسب برای اعمال بر روی سیگنال های هواشناسی دما و بارش به منظور هموارسازی، جداسازی مولفه های بسامدی با اهمیت و حذف نوفه های بسامد بالای بی اهمیت است. طراحی این پالایه ها، هم در حوزه زمان و هم در حوزه بسامد امکان پذیر است که در این تحقیق طراحی و اعمال پالایه در حوزه زمان انجام شده است. نتایج اهمیت انتخاب پالایه ی مناسب در تحلیل محتوای طیفی موجود در سیگنال هواشناسی را نشان می دهد. با پالایش سیگنال خام دما و بارش ماهانه طی دوره آماری 1979 تا 2021 در ایستگاه های تهران و تبریز به مولفه های فصلی، سالانه و بین سالی، ارتباط خطی بین این مولفه ها به طور مجزا توسط ضریب همبستگی پیرسون مورد بررسی قرار گرفته و شباهت ها و تفاوت ها با هم مقایسه شده اند. همچنین پالایه همینگ نسبت به پالایه میانگین متحرک ساده، عملکرد بهتری را در تضعیف نوسان های گیبس در بخش های جانبی پاسخ بسامدی پالایه نشان می دهد. البته انتخاب تعداد وزن بیشتر در طراحی پالایه می تواند در بهبود عملکرد پالایه اثرگذار باشد. این مساله در زمانی که تعداد مولفه های با اهمیت بیشتری در طیف بسامدیِ سیگنال هواشناسی وجود دارند، بایستی بیشتر مورد توجه قرار گیرد.

Description: The Authors present a critical assessment of ODR+ mechanisms to settle Belt & Road Initiative disputes (primarily smart courts and smart contracts).〈div class="enclosure"〉〈/div〉

Description: 〈div〉〈p〉〈em〉A Geographic Information System (GIS) includes of a hardware and software which are used for purposes such as to capture, store, evaluate, administer and distribute spatial data. GIS has a vast array of spatial analysis tools such as GIS viewer, Geodatabase, mapping tools, modelling tools etc. At present GIS is broadly used in conjunction with multi criteria decision analysis method to perform infrastructure studies and transportation studies such as road and rail. Multi criteria decision analysis can be applied in vehicle routing, site selection, scenario evaluation, land suitability, impact assessment, and location allocation for different sectors. According to majority of the literature, main factors considered in designing railway with GIS are land use, slope, drainage and soil. When multi criteria decision analysis is combined with GIS, it considers different geographical data models, spatial dimension of the evaluating criteria and decision alternatives in those criteria. The best route out of various alternate alignments has been designed using GIS thematic maps and network analysis in ArcGIS as a base. As a conclusion, this review study proves that multi criteria decision analysis combined with GIS plays a major role in modern railroad construction. 〈strong〉 〈/strong〉〈/em〉〈/p〉〈/div〉

Description: 〈p〉In late 2021, China experienced a severe electricity supply crisis that affected 20 provinces. Industrial activity was curtailed, and even households suffered prolonged outages in some areas. The country is no stranger to periodic energy supply shortages and in many outages in the past, the principal causes involved either poor policy coordination or a clash […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-forum-the-2021-energy-crisis-implications-for-chinas-energy-market-and-policies/"〉Oxford Energy Forum – The 2021 energy crisis: Implications for China’s energy market and policies – Issue 131〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉〈em〉Air pollution is mainly due to the release of pollutants into the atmosphere which are detrimental to the planet and human health in particular〈/em〉〈em〉.〈/em〉〈em〉 Monitoring for the air quality parameters is important because it may lead to the adverse effects on the environment. The quantitative analysis of the air pollution spreads over the Bangalore city is carried out using two different data sources, one from ground monitoring stations and the other from the satellite derived data. Ambient Air Quality data for Bangalore region recorded by Karnataka State Pollution Control Board (KSPCB) for 2018–2020 were analysed in the open source GIS platform. Air quality parameters like aerosol optical depth (AOD), Nitrogen di-oxide (NO〈sub〉2〈/sub〉) etc. were collected from Moderate Resolution Imaging Spectro-radiometer (MODIS) and Ozone monitoring instruments for spatial analysis. Data were analysed and compared and found that satellite based data of NO〈sub〉2〈/sub〉 from the sensors provide a reliable values in ground-level exposure for a larger urban region.〈/em〉〈/p〉

Description: 〈p〉Following Russia’s invasion of Ukraine on 24 February 2022, energy markets are in turmoil. Oil and gas prices are rising and exhibiting high volatility as the markets grapple with the impact of sanctions and the prospect of reduced flows from Russia . China is heavily exposed to Russian commodity exports and to global markets. The […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/the-russian-invasion-of-ukraine-and-chinas-energy-markets/"〉The Russian invasion of Ukraine and China’s energy markets〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉In this podcast, James Henderson talks to Anouk Honoré about her forthcoming article “Demand-side factors behind the historical gas price rally in Europe in 2021”. This article is part of a trilogy entitled “A Series of Unfortunate Events” that analyses the main supply and demand factors in the European gas market(s) that contributed to rising gas prices since summer […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-podcast-a-series-of-unfortunate-events-demand-side-factors-in-the-european-gas-price-rally-in-2021/"〉Oxford Energy Podcast – A Series of Unfortunate Events:​ Demand-Side Factors in the European Gas Price Rally ​in 2021〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/02/Podcast-132-EU-Gas-Demand.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/02/Podcast-132-EU-Gas-Demand.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉In this latest OIES podcast James Henderson talks to Mike Fulwood and Jack Sharples about their latest research on the possible impact of an interruption of Russian gas supplies to Europe. After a quick update on current gas prices Jack Sharples reviews the current state of gas supply to Europe, looking at flows in 2021 […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-podcast-the-russian-invasion-of-ukraine-implications-for-the-european-gas-market/"〉Oxford Energy Podcast – The Russian invasion of Ukraine – implications for the European gas market〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-135-The-Russian-invasion-of-Ukraine-–-implications-for-the-European-gas-market.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-135-The-Russian-invasion-of-Ukraine-–-implications-for-the-European-gas-market.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉This month’s OIES Oil Monthly Special Issue assesses the implications of the Ukraine war on our short-term oil market outlook for market balances and prices to 2023. The analysis considers two scenarios. A Reference case in which self-sanctioning measures and obstacles in redirecting Russian crude flows due to financing and shipping constraints results in a […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oies-oil-monthly-issue-12/"〉OIES Oil Monthly – Special Issue 12〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: در این مقاله سری زمانی یونوسفر با استفاده از سه مدل شبکه‌های عصبی مصنوعی (ANNs)، سیستم استنتاج عصبی-فازی سازگار (ANFIS) و ماشین بردار پشتیبان (SVM) مدل‌سازی شده و سپس پیش‌بینی می‌شود. جهت انجام این تحقیق از مشاهدات ایستگاه GNSS تهران (N69/35 ، E33/51) که یکی از ایستگاه‌های شبکه جهانی IGS است، در سال‌های 2007 الی 2018 استفاده شده است. پارامترهای سال (year)، روز از سال (DOY)، ساعت (time)، شاخص فعالیت‌های خورشیدی (F10.7) و شاخص‌های فعالیت‌های ژئومغناطیسی (Kp and DST) به عنوان ورودی هر سه مدل در نظر گرفته شده و خروجی، مقدار TEC خواهد بود. برای مرحله آزمون دقت هر سه مدل، مشاهدات دو سال 2014 و 2018 از مرحله آموزش کنار گذاشته شده‌اند. دلیل انتخاب این دو سال، بررسی دقت مدل‌ها در زمان فعالیت‌های شدید خورشیدی (2014) و فعالیت‌های آرام خورشیدی (2018) است. نتایج حاصل از هر سه مدل با TEC حاصل از مدل مرجع بین‌المللی یونوسفر 2016 (IRI2016) و همچنین خروجی‌های شبکه جهانی IGS مقایسه شده است. همچنین از شاخص‌های آماری ضریب همبستگی، خطای نسبی و جذر خطای مربعی میانگین (RMSE) جهت بررسی دقت و صحت سه مدل استفاده شد. کمینه RMSE محاسبه شده برای مدل SVM، 11/3 TECU بدست آمده که در مقایسه با سایر مدل‌ها، از دقت بالاتری در مدل‌سازی و پیش‌بینی سری زمانی TEC یونوسفر در دوره فعالیت‌های آرام و شدید خورشیدی برخوردار است.

Description: An ensemble of elementary radiators is generated on the basement rock because of the applied stresses in the preparation zone of the earthquakes in the earth crust. Considering such an ‘ensemble’ as the source of electromagnetic signals, the strength of the electric field is estimated at different distances and frequencies laying in range (3 – 27 kHz) at three different conductivities of the crustal layers (10-8, 10-9, 10-10 S/m). The results of the computation are presented in this paper. Moreover, propagation distances for the seismogenic VLF emissions have also been calculated in the frequency band (3 – 27 kHz) at the conductivities laying in the range (10-8 - 10-10 S/m) within the limit of detectability of measuring instruments (10-7 V/m). It is observed that these distances increase with the decrease of conductivity of the middle layer of crust. Furthermore, theoretical results of computations are verified from the experimental observations of the seismic event that occurred at the distance of 698 km from the observing station at Chaumuhan Mathura (Geographic lat. 27.490N, long. 77.670E). In addition to this, the generation and propagation mechanisms of seismo-electromagnetic radiations have also been discussed briefly.

Description: جت حاره وابسته به نوسان شبه دوسالانه QBO (Quasi Biennial Oscillation) به عنوان یک عامل تاثیر‌گذار بر جنب‌حاره وردسپهرزبرین مطرح است. در این پژوهش اثر QBO بر شکست امواج روی شرق مدیترانه و غرب‌آسیا از دیدگاه عرضهای بحرانی بررسی می‌شود. با استفاده از داده‌های بازتحلیل ERA-Interim بین سالهای 2018-1979، کمیت‌های شار فعالیت موج و شیو تاوایی پتانسیلی شبه زمینگرد در فازهای شرقی و غربی نوسان شبه‌دوسالانه QBO محاسبه و بررسی شده‌اند. نتایج نشان داد که در شکست امواج روی غرب‌آسیا همراه با استقرار و تقویت جت‌ها در بالادست و پایین‌دست ناوه‌ها، مقادیر منفی شیو تاوایی پتانسیلی شبه زمینگرد شکل می‌گیرند. در فاز شرقی نسبت به فاز غربی QBO جت‌ها و مقادیر منفی شیو تاوایی پتانسیلی شبه زمینگرد در بالادست و پایین‌دست ناوه‌ها بیشتر تقویت می‌شوند. بنابراین در فاز شرقی نسبت به فاز غربی QBO تقویت بازتاب استواسوی ناوه از عرضهای بحرانی موجب افزایش گردش واچرخندی و نفوذ بیشتر ناوه به عرضهای پایین‌تر می‌شود. در شکست چرخندی امواج نیز جت‌حاره شرقی وابسته به QBO سبب تقویت جت‌ها در عرضهای میانی می‌شود. بنابراین افزایش بازتاب قطب‌سوی ناوه از عرضهای بحرانی در بالادست و پایین‌دست ناوه سبب تقویت گردش چرخندی ناوه در فاز شرقی می‌شود. در نتیجه در فاز شرقی مولفه نصف‌النهاری شار فعالیت موج در پایین‌دست ناوه افزایش می‌یابد و شکست امواج روی غرب‌آسیا در فاز شرقی قوی‌تر از فاز غربی صورت می-گیرد. در حالیکه در شکست واچرخندی امواج روی غرب مدیترانه جت حاره غربی وابسته QBO سبب تقویت عرضهای بحرانی نسبت به فاز شرقی می‌شود.

Description: با توجه به پیچیدگی و تنوع ساختار‌ تکتونیکی در منطقه خاورمیانه استفاده از روشی که بتواند عمق موهو را با بیشترین همخوانی با این ساختارها را ارائه دهد، از اهمیت ویژه‌ای برخوردار است. در این مقاله به مقایسه عمق موهو بدست‌آمده در منطقه خاور‌میانه با استفاده از دو شیوه متفاوت 1) وارون‌سازی گرانی منشور‌های کروی و 2) تخمین عمق موهو با بکار‌گیری منشور‌های کروی و استفاده از مدل پوسته لرزه‌ایCRUST1.0 ، می‌پردازیم. در حالت کلی بدست آوردن عمق از داده‌های گرانی یک مساله وارون غیرخطی است. در هر دو شیوه داده‌های گرانی با استفاده از روش یودا برگردان می‌شوند. با توجه به وسعت منطقه، استفاده از منشورهای کروی بجای منشورهای تخت در روش وارون سازی بکار رفته علاوه بر در نظر گرفتن انحنای زمین موجب کارآمدی روش نیز می‌گردد. کمینه عمق موهوی بدست آمده از روش اول ۱۲ کیلومتر مربوط به بخش‌هایی از اقیانوس هند و بیشینه عمق موهو ۵۴ کیلومتر مربوط به قسمت‌های غربی فلات تبت است که با مرز صفحات و ساختارهای تکتونیکی همبسته است. محدوده عمق موهو در روش دوم در بازه‌ ۵/۷ تا ۴۹ کیلومتر است که مقدار کمینه مربوط به بخش‌هایی از اقیانوس هند و مقدار بیشینه مربوط به قسمت‌هایی از زاگرس است. مقایسه نتایج دو روش نشان می‌دهد که نتایج حاصل از روش اول بخاطر وارون سازی داده‌های گرانی‌سنجی نسبت به روش دوم که از مدل پوسته لرزه‌ای CRUST 1.0 برای تخمین عمق موهو استفاده کرده، کاملا با مرز صفحات همخوانی داشته و کلیه ساختار‌های تکتونیکی منطقه را نشان‌ می‌دهد.

Description: We investigate the capability of the WRF/Chem model in the simulation of some criteria air pollutants, during a major air pollution episode between 16 and 21 December 2017. In this study, by employing the EDGAR-HTAP_v2 global emissions data in the WRF/Chem model, we evaluate the simulations of the surface mixing ratios of NO2, SO2, and CO. The RADM2 chemical mechanism with MADE-SORGAM aerosol scheme has been used as the chemical option of the WRF/Chem model, to simulate the meteorology-chemistry interactions. The variations of the time series of the pollutants and the comparisons of the results in Tehran with the measurement data showed that although the WRF/Chem simulations in Tehran presented considerable over-estimations, but the model’s performance with regard to the time variations of the concentrations of the gaseous agents over the polluted episode is acceptable, and therefore, could be considered in the operational air quality systems. Since emission data are not available for many metropolitan areas over Iran, the HTAP_v2 global dataset could be used as the emissions data with reliable accuracy for the numerical air quality models.

Description: تجزیه و تحلیل احتمالی وقایع خشکسالی در مدیریت و برنامه‌ریزی مناسب سیستم‌های منابع آب نقش مهمی دارد. به طور خاص، برآورد دوره‌های بازگشت این پدیده می‌تواند اطلاعات مفیدی برای استفاده مناسب از آب در شرایط خشکسالی فراهم کند. در این مطالعه، توانمندی دو مدل سری CMIP5 در شبیه‌سازی ویژگی‌های احتمالاتی توام شدت و مدت این بلیه با استفاده از مفصل مورد بررسی قرار گرفته و تحلیل فراوانی دو متغیره مفصل-مبنا بر حسب شدت و مدتSPEI3 برای دوره پایه و دوره آتی در بخش جنوبی حوضه کارون انجام شده است. رویداد خشکسالی در سری SPEI3 به صورت تعدادی متوالی از این رویداد در فواصل زمانی که مقادیر SPEI کمتر از 1- است تعیین شد. پس از شناسایی خشکسالی، چندین ویژگی مانند شدت، مدت، سختی و ... را می‌توان تعیین کرد. از توابع مفصل و توزیع‌های حاشیه‌ای برای محاسبه دوره‌های بازگشت توام شدت و مدت به دو صورت "و" و "یا" استفاده و تأثیرات تغییرات اقلیمی بر ویژگی‌های خشکسالی آینده با استفاده از دو مدل اقلیم (HadGEM2-es و IPSL-CM4-MR) تحت سناریوهای RCP8.5 و RCP4.5 طی دوره 2050-2021 ارزیابی شد. نتایج نشان داد که توابع فرانک (ایستگاهی) و گامبل (CRU و دو مدل اقلیمی) بهترین انتخاب برای برازش بر مقادیر مدت و شدت استخراج شده از سری SPEI-3 بودند. مدل HadGem توانمندی خوبی را در شبیه‌سازی رفتار احتمالاتی توام خشکسالی طی دوره پایه نشان داد. همچنین پیش‌نگری‌ها نشان داد اهواز در آینده نزدیک در مقایسه با دوره پایه تحت دو سناریو، خشکسالی‌های شدیدتری بویژه در شبیه‌سازی مدل HadGEM2-es تجربه خواهد کرد.

Description: در این پژوهش روش تنظیم سطح برای وارون‌‌سازی مسائل گرانی‌سنجی استفاده شده است. با توجه به اینکه در مسائل وارون گرانی سنجی همواره با عدم یکتایی روبه رو هستیم، روش تنظیم سطح کمک می نماید تا با منظم سازی مسئله به کاهش در عدم یکتایی جواب نزدیک تر شویم. این روش دارای یک الگوریتم مناسب است که حساسیت مطلوبی در تعیین دقیق مرزها در مقطع جانبی دارد. همچنین برای بهینه‌ سازی و کاهش ابعاد پارامترهای مسئله، توابع پایه شعاعی برای نشان دادن عملکرد تابع تنظیم سطح انتخاب می شود. در این پژوهش الگوریتم مذکور برای بررسی نقاط ضعف و قوت آن و به منظور اعمال برداده های ژئوفیزیکی گرانی سنجی، کد نویسی و برنامه نویسی صورت گرفته است. در نتیجه با اعمال بر مدل‌های مصنوعی مشابه گنبد نمکی و مکعب ساده و نیز اعمال نویز تصادفی مختلف، مورد آزمایش قرار گرفت و نهایتاً برای تست واقعی از داده های معدن موبرون کانادا استفاده شده است.

Description: بخارآب یکی از مهم‌ترین شاخص‌های جوی است که تعیین دقیق آن به افزایش دقت مدل‌های عددی هواشناسی کمک فراوانی می‌کند. امروزه با استفاده از مشاهدات GNSS و به‌کارگیری روش توموگرافی می‌توان ضرایب شکست تر در هر یک از المان‌های حجمی در نظر گرفته‌شده را برآورد کرد. استفاده از مشاهدات رخداد آکولتیشن می‌تواند باعث افزایش تعداد مشاهدات از جنس پارامترهای جوی حتی در نقاطی که مشاهدات ایستگاه‌های GNSS حضور ندارد، گردد. هدف از این تحقیق تلفیق مشاهدات آکولتیشن با مشاهدات GPS به‌منظور بالا بردن دقت ضرایب شکست برآورد شده در توموگرافی تابعی تروپوسفر است. به‌منظور برآورد نمودن مجهولات مسئله توموگرافی از مدل تابعی به کمک هارمونیک‌های کلاه کروی به همراه توابع متعامد تجربی برای تشکیل مدل سه‌بعدی استفاده‌شده است. همچنین از توابع پایه‌ی اسپیلاین برای نمایش توزیع ضرایب شکست تر در زمان و تشکیل مدل چهاربعدی بهره گرفته‌شده است. منطقه موردمطالعه، شبکه‌ ایستگاه‌های دائمی در کالیفرنیا می‌باشد بطوریکه پروفیل ضرایب شکست تر حاصل از توموگرافی در دو اپک زمانی (دو فصل مختلف) محاسبه گردیده و با داده‌های رادیوسوند مقایسه می‌شوند. نتایج نشان می‌دهد که استفاده از مشاهدات آکولتیشن در کنار مشاهدات زمینی GPS در توموگرافی انجام‌شده با استفاده از مدل‌های تابعی سه‌بعدی و چهاربعدی می‌تواند مقدار RMSE پروفیل‌های ضرایب شکست تر را تا حدود 8 درصد نسبت به توموگرافی انجام‌شده فقط با استفاده از مشاهدات GPS بهبود دهد. نهایتا نشان داده‌شده که اضافه نمودن مشاهدات آکولتیشن باعث تغییر در تأخیر تروپوسفری تر برآورد شده برای منطقه موردمطالعه در حدود 4 سانتی‌متر می‌گردد.

Description: دمای سطح زمین (LST) که حاصل اندرکنش جو ـ زمین است، به دلیل تأثیرپذیری از پوشش سطح زمین، رطوبت خاک، آلبیدو، زبری سطح و اندرکنش این عوامل با هواسپهر، می‌تواند تغییرات شرایط حرارتی سطح زمین را آشکار نماید. در پژوهش حاضر از داده‌های LST شب‌‌هنگام سنجنده‌ی مودیس ماهواره‌های ترا و آکوا (MOD11C3 & MYD11C3) که از وبگاه http://earthdata.nasa.gov دریافت گردید، برای برآورد LST در حوضه‌ی آبریز جازموریان طی سال‌های 2019-2003 استفاده شد. پس از فراهم‌سازی داده‌ها با گام‌های زمانی ماهانه و مکانی 5 کیلومتر، محاسبات بر روی دو ماتریس ماهانه و فصلی انجام گردید و به تهیه‌ی خروجی‌های آماری‌ـ-فضایی منطبق با هدف تحقیق، در محیط نرم‌افزارهای Excel، ENVI و GIS اقدام شد. نتایج نشان داد؛ LST شب‌هنگام در حوضه‌ی آبریز جازموریان، طی دوره‌ی آماری مورد مطالعه حدود °C 1 افزایش یافته‌است. این افزایش در دمای کمینه ‌بیش از افزایش در دمای بیشینه بوده‌است. توزیع فضایی LST شب‌هنگام نیز، بیان‌گر دامنه‌ی گسترده‌ای از دماها از°C10 - تا°C 35 + است که بیشینه‌ی آن در مناطق پست و کم‌ارتفاع مرکزی و جنوبی و کمینه‌ی آن در ارتفاعات شمالی حوضه برآورد گردید. همچنین برآورد فضایی ناهنجاری LST شب‌هنگام، ضمن تأیید روند افزایشی LST، بیشترین/کمترین ناهنجاری‌ مثبت LST را به ترتیب در بخش‌های مرکزی و غربی/بخش‌های شرقی و ارتفاعات شمالی حوضه نشان داده‌است. این شرایط می‌تواند به عنوان نمایه‌ای از تغییر اقلیم مورد توجه قرار گرفته و منجر به تغییر برخی از فراسنج‌های محیطی از قبیل رطوبت نسبی، تبخیر و تعرق، رطوبت سطح خاک، ماندگاری برف، دمای نقطه‌ی شبنم و انرژی بازتابی شبانه شود.

Description: Some extreme precipitations have occurred in Iran in recent years. This paper is devoted to the study of extreme precipitations in the west of Iran, affected by combination of atmospheric pressure patterns in the period of 1987–2016. At first, monthly precipitations for seven synoptic stations of the west of Iran in autumn and winter with positive anomalies greater than 100% were identified. Then, for statistical-dynamical analysis, the El-Nino Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Madden–Julian Oscillation (MJO) indices were used. Results showed that the extreme precipitations had occurred during moderate to strong El-Nino, while MJO was critical and strong, in phases 2 and 8, and NAO was in positive phase. The anomalies of the MJO index in case studies had positive values. The NAO for case studies has entered a positive phase from a strong negative phase a few days before extreme precipitation. Analyzing the relationship between the NAO and the MJO with lagged composites showed when the MJO leads the NAO, significant positive NAOs are found for phases 2, and negative NAOs for phases 8, indicating a significant influence of the MJO on NAO. The synoptic-dynamic analysis showed that three low pressure and one high pressure were the dominant systems that have been effective in producing extreme precipitation. Examination of the moisture fluxes revealed that the main humidity sources of the heavy precipitation were the Arabian Sea due to easterly winds that travel a long distance over the north west of Indian Ocean to the Arabian Sea.

Description: An integrated GIS, Remote sensing, and Geophysical techniques have been successfully applied to generate the previously non-available groundwater prospectivity map for the present study area. Selected thematic maps were integrated using the weighted sum tool of the spatial analyst tool of the ArcGIS software. The five thematic maps used are: lithology map, drainage density map, slope map, lineaments density map, and the topographic map of the area. The groundwater prospectivity map generated was reclassified into low, moderate, high, and very high potential zones on the basis of their assigned layer rank, which also depends on their degree of influence on groundwater occurrence. Areas around Gombe, Wuyo, Deba, Alkaleri, Kaltungo, Misau, Nafada, Bajoga towns are the regions that showed very high prospects for groundwater occurrence. Data processing filters such as: horizontal derivatives, Analytic signal processing, 3D-Euler depth estimation was applied on the magnetic data in order to map structures and lithologic contacts before its subsequent integration with other structural lineaments as a thematic layer. Vertical Electrical Sounding (VES) data were used to compute hydraulic conductivity, and Transmisivity etc. for the acquiferous layers identified. The results of the present study showed some regions that are classified as highly prospective to be consistent with high transmisivity and high yield values. The final outcome (groundwater potential map) of this research demonstrated that GIS/remote sensing, and the geophysical technique employed is a very powerful tool for generating groundwater prospectivity map, which is very vital in terms of planning for groundwater exploration and exploitation.

Description: امروزه انواع شبکه‌های عصبی مصنوعی در حوزه های مختلف علوم جو و اقلیم‌شناسی برای اهدافی نظیر طبقه‌بندی، رگرسیون و پیش-بینی استفاده می‏شوند. اما سوال اساسی در استفاده از شبکه‌های عصبی مصنوعی، نحوه طراحی و معماری آنهاست. یکی از نکات مهم در استفاده از شبکه‌های عصبی مصنوعی که باید مد نظر طراحان قرار بگیرد، انتخاب الگوریتم مناسب برای آموزش شبکه است. در این مقاله، شش روش مختلف آموزش شبکه عصبی پرسپترون چند لایه شامل روشهای منظم سازی بیزی، لِوِنبرگ-مارکوات و گرادیان مزدوج پاول-بل، الگوریتم شبه نیوتنی BFGS، گرادیان مزدوج فلچر-پاول و گرادیان مزدوج مقیاس شده برای پیش‌بینی ماهانه بارش کشور مورد بررسی و مقایسه قرار میگیرند. برای این منظور، یک شبکه عصبی پرسپترون برای پس پردازش خروجی بارش ماهانه مدل ECMWF طراحی می‏شود که برای آموزش آن از داده‏های ERA5 و روشهای آموزش مختلف استفاده می‏شود. برای بررسی عملکرد شش روش آموزش مختلف، مقدار سه شاخص ضریب همبستگی، میانگین مربعات خطا و نیز شاخص نش-ساتکلیف برای هر مدل محاسبه گردید. همچنین، عملکرد روشهای مذکور در مناطق جغرافیایی مختلف کشور برای ماه ژانویه، به عنوان نمونه، مورد ارزیابی قرار گرفت. نتایج حاصل از مقایسه شاخصها نشان داد که عملکرد دو روش منظم سازی بیزی و لِوِنبرگ-مارکوات، در مقایسه با چهار روش دیگر برای آموزش شبکه عصبی بهتر است. همچنین این دو روش توانستند، در مقایسه با داده‏های مدل ECMWF، قبل از پس پردازش، نتایج با دقت بیشتری را بدست آورند.

Description: بررسی رخداد توأم چرخندها و تغییر تراز فشار وردایست اطلاعات مفیدی دربارۀ ویژگی‌های جو به‌ویژه در ارتباط با رخداد بارش‌های فراگیر ایران به‌دست می‌دهد؛ زیرا از عواملی که منجر به بروز بارش‌های فراگیر در ایران می‌شود چرخندهای ورودی به کشور است. شناخت ساز وکارهای مرتبط با چرخند‌ها می‌تواند در شناخت بهتر و پیش‌بینی آنها موثر باشد. به‌همین دلیل در پژوهش حاضر ارتباط وردایست با چرخندهای تاثیرگذار بر بارش‌های فراگیر ایران مورد بررسی قرار گرفت. جهت انجام پژوهش از داده‌های دما و ارتفاع ژئوپتانسیل پایگاه داده ECMWF و جهت انتخاب روزهای توأم با بارش فراگیر ایران نیز از داده‌های پایگاه اسفزاری (نسخۀ سوم) استفاده شده‌است. با توجه به این‌که مطالعه‌ی تمام روزهای توأم با بارش فراگیر در این پژوهش امکان‌پذیر نبود، از میان تمام روزهای توأم با بارش فراگیر، روزهایی که درصد مساحت تحت پوشش بارش در آنها بیشتر بود، برای ماه‌های مختلف انتخاب شد. در نهایت درطول دوره‌ی مورد مطالعه 8 روز در 8 ماه مختلف انتخاب شد. برای هر روز منتخب، چرخند فعال شناسایی و ویژگی‌‌های وردایست در زمان شروع چرخند و روز رخداد بارش فراگیر بررسی شد. براساس نتایج به دست آمده از این پژوهش مشخص شد که در تمام 8 روز مورد واکاوی، در روز شروع فعالیت چرخند و در روز توأم با بارش فراگیر برروی ایران، تراز فشار وردایست تفاوت‌های قابل توجهی با مناطق هم عرض (و اطراف) خود دارد. در این هنگام تراز فشار وردایست مقادیر عددی بزرگ‌تری را نشان می‌دهد.

Description: 〈p〉This paper aims to examine consumer behaviour towards, and the willingness to adopt, ‘green steel’ in the automotive sector. Semi-structured interviews were held with experts from global, regional and country-specific industry associations and automakers. This paper appraises potential demand for green steel within different vehicle types (based both on size and powertrain) and shows that manufacturers […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/steeling-the-race-green-steel-as-the-new-clean-material-in-the-automotive-sector/"〉Steeling the race: ‘Green steel’ as the new clean material in the automotive sector〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉In this podcast David Ledesma discusses the implications of Russia’s invasion of Ukraine for global oil markets with Bassam Fattouh, Director of OIES based on his latest paper: Russia-Ukraine crisis: Implications for global oil markets with Andreas Economou and Ahmed Mehdi. In this wide-ranging discussion, Bassam Fattouh discusses what the potential loss of Russian oil […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-podcast-russia-ukraine-crisis-implications-for-global-oil-markets/"〉Oxford Energy Podcast – Russia-Ukraine crisis – Implications for global oil markets〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-134-Russia-Ukraine-crisis-Implications-for-global-oil-markets.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-134-Russia-Ukraine-crisis-Implications-for-global-oil-markets.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉In September-October 2021, China experienced a severe electricity supply crisis that impacted over twenty provinces, leading to industrial curtailment and residential supply cuts in some areas. In this podcast David Ledesma discusses the causes and implications of this supply crisis with Michal Meidan Director of the Gas Research Programme & the China Energy Research Programme […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-podcast-the-2021-energy-crisis-implications-for-chinas-energy-market-and-policies/"〉Oxford Energy Podcast – The 2021 energy crisis: Implications for China’s energy market and policies〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-133-The-2021-energy-crisis-Implications-for-Chinas-energy-market-and-policies.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-133-The-2021-energy-crisis-Implications-for-Chinas-energy-market-and-policies.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: Through empirical and policy analysis, this Article explores a fundamental disconnect between the statutory objectives of the Securities and Exchange Commission and the actual outcome of its policies in digital-asset markets.〈div class="enclosure"〉〈/div〉

Description: 〈p〉This paper considers potential import routes for low-carbon and renewable hydrogen (H2) to main European markets like Germany. In particular, it analyses claims made by Hydrogen Europe and subsequently picked up by the European Commission in its Hydrogen Strategy that there will be 40GW of electrolyser capacity in nearby countries providing hydrogen imports to Europe […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/potential-development-of-renewable-hydrogen-imports-to-european-markets-until-2030/"〉Potential development of renewable hydrogen imports to European markets until 2030〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉After weeks of tensions, Russian President Vladimir Putin ordered Russian troops to invade Ukraine, prompting an international sanctions response targeting Russia’s economy but not directly its oil supplies or energy payments. But as sanctions on Russia intensified and as financial institutions started to refuse financing Russia-related transactions, including opening letters of credit or clearing payments […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/russia-ukraine-crisis-implications-for-global-oil-markets/"〉Russia-Ukraine crisis: Implications for global oil markets〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉The specter of climate change has impacted shareholder sentiment making many market participants evaluate their business models in accordance with Cop-26 pledges – looking for ways of winning the mandate for capital in a sustainable way. The most familiar approach to reducing carbon footprint is by creating ‘GHG-verified’ claims. Typically, these involve a verified account […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/ghg-verified-mechanisms-for-internationally-traded-crude-oil-and-possible-impact-on-oil-benchmarks/"〉GHG-verified mechanisms for internationally traded crude oil and possible impact on oil benchmarks〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉Central banks worldwide are stepping up actions in relation to climate change and taking on an increasingly important role in supporting the energy transition. Given the prominent role that central banks play in the financial markets and in influencing financing conditions, they can act as a powerful catalyst in addressing climate change. But their involvement […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/central-banks-green-shift-and-the-energy-transition/"〉Central Banks’ ‘Green Shift’ and the Energy Transition〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉On 8 March 2022, the European Commission published the outline of a plan to make Europe independent from Russian fossil fuels well before 2030, starting with gas, in light of Russia’s invasion of Ukraine. The Commission noted that EU gas imports from Russia in 2021 (pipeline and LNG combined) totalled 155 billion cubic metres (bcm), […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/the-eu-plan-to-reduce-russian-gas-imports-by-two-thirds-by-the-end-of-2022-practical-realities-and-implications/"〉The EU plan to reduce Russian gas imports by two-thirds by the end of 2022: Practical realities and implications〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: In this paper, the existence (invariance) and stability (locally and globally) of relay interlayer synchronisation (RIS) are investigated in a chain of multiplex networks. The local dynamics of the nodes in the symmetric positions layers on both sides of the non-identical middlemost layer(s) are identical. The local and global stability conditions for this synchronisation state are analytically derived based on the master stability function approach and by constructing a suitable Lyapunov function, respectively. We propose an appropriate demultiplexing process for the existence of the RIS state. Then the variational equation transverse to the RIS manifold for demultiplexed networks is derived. In numerical simulations, the impact of interlayer and intralayer coupling strengths, variations of the system parameter in the relay layers and demultiplexing on the emergence of RIS in triplex and pentaplex networks are explored. Interestingly, in this multiplex network, enhancement of RIS is observed when a type of impurity via parameter mismatch in the local dynamics of the nodes is introduced in the middlemost layer. A common time-lag with small amplitude shift between the symmetric positions and central layers plays an important role for the enhancing of relay interlayer synchrony. This analysis improves our understanding of synchronisation states in multiplex networks with nonidentical layers.

Description: We investigate the response characteristics of a two-dimensional neuron model exposed to an externally applied extremely low frequency (ELF) sinusoidal electric field and the synchronization of neurons weakly coupled with gap junction. We find, by numerical simulations, that neurons can exhibit different spiking patterns, which are well observed in the structure of the recurrence plot (RP). We further study the synchronization between weakly coupled neurons in chaotic regimes under the influence of a weak ELF electric field. In general, detecting the phases of chaotic spiky signals is not easy by using standard methods. Recurrence analysis provides a reliable tool for defining phases even for noncoherent regimes or spiky signals. Recurrence-based synchronization analysis reveals that, even in the range of weak coupling, phase synchronization of the coupled neurons occurs and, by adding an ELF electric field, this synchronization increases depending on the amplitude of the externally applied ELF electric field. We further suggest a novel measure for RP-based phase synchronization analysis, which better takes into account the probabilities of recurrences.

Description: We investigate the response characteristics of a two-dimensional neuron model exposed to an externally applied extremely low frequency (ELF) sinusoidal electric field and the synchronization of neurons weakly coupled with gap junction. We find, by numerical simulations, that neurons can exhibit different spiking patterns, which are well observed in the structure of the recurrence plot (RP). We further study the synchronization between weakly coupled neurons in chaotic regimes under the influence of a weak ELF electric field. In general, detecting the phases of chaotic spiky signals is not easy by using standard methods. Recurrence analysis provides a reliable tool for defining phases even for noncoherent regimes or spiky signals. Recurrence-based synchronization analysis reveals that, even in the range of weak coupling, phase synchronization of the coupled neurons occurs and, by adding an ELF electric field, this synchronization increases depending on the amplitude of the externally applied ELF electric field. We further suggest a novel measure for RP-based phase synchronization analysis, which better takes into account the probabilities of recurrences

Description: The data file `CENOGRID_Loess_20.txt` contains the astronomically tuned deep-sea benthic foraminifer carbon (δ¹³C) and oxygen (δ¹⁸O) isotope reference records uniformly covering the entire Cenozoic. The first column is the tuned age in Ma, the second column the δ¹³C, and the third column the δ¹⁸O record. The original calculations were performed using the CRP Toolbox for MATLAB. In order to avoid installing the toolbox and for better performance, the functions for calculating RP and RQA were here reimplemented, providing identical result. To reproduce the RPs in Fig. 2, use the script `perform_rp.m`, for reproducing the determinism values and upper confidence bounds, use the script `perform_rqa.m`.

Description: This article examines the effects of extreme weather events on internal migration in Mongolia. Our focus is on dzuds , extremely harsh winters characterized by very cold temperature, snowfall anomalies, and/or storms causing very high livestock mortality. We exploit exogenous variation in the intensity of extreme winter events across time and space to identify their causal impacts on permanent domestic migration. Our database is a time series of migration and population data at provincial and district level from official population registries, spanning the 1992-2018 period. Results obtained with a two-way fixed effects panel estimator show that extreme winter events cause significant and sizeable permanent out-migration from affected provinces for up to two years after an event. These effects are confirmed when considering net change rates in the overall population at the district level. The occurrence of extreme winter events is also a strong predictor for declines in the local population of pastoralist households, the socio-economic group most affected by those events. This suggests that the abandonment of pastoralist livelihoods is an important channel through which climate affects within-country migration.

Description: Background: Women in rural Bangladesh face multiple, inter-related challenges including food insecurity, malnutrition, and low levels of empowerment. We aimed to investigate the pathway towards empowerment experienced by women participating in a three-year nutrition-sensitive homestead food production (HFP) program, which was evaluated through the Food and Agricultural Approaches to Reducing Malnutrition (FAARM) cluster-randomized controlled trial. Methods: We conducted 44 in-depth interviews and 12 focus group discussions with men and women in both intervention and control communities of the FAARM study site in rural, north-eastern Bangladesh. Using a modified grounded theory approach to data collection and analysis, we developed a framework to explain the pathway towards empowerment among HFP program participants. Results: The analysis and resulting framework identified seven steps towards empowerment: 1) receiving training and materials; 2) establishing home gardens and rearing poultry; 3) experiencing initial success with food production; 4) generating social or financial resources; 5) expanding agency in household decision-making; 6) producing renewable resources (e.g. farm produce) and social resources; and 7) sustaining empowerment. The most meaningful improvements in empowerment occurred among participants who were able to produce food beyond what was needed for household consumption and were able to successfully leverage these surplus resources to gain higher bargaining power in their household. Additionally, women used negotiation skills with their husbands, fostered social support networks with other women, and developed increased self-efficacy and motivation. Meanwhile, the least empowered participants lacked support in critical areas, such as support from their spouses, social support networks, or sufficient space or time to produce enough food to meaningfully increase their contribution and therefore bargaining power within their household. Conclusions: This study developed a novel framework to describe a pathway to empowerment among female participants in an HFP intervention, as implemented in the FAARM trial. These results have implications for the design of future nutrition-sensitive agriculture interventions, which should prioritize opportunities to increase empowerment and mitigate the barriers identified in our study. Trial registration: FAARM is registered with ClinicalTrials.gov (NCT02505711).

Description: The ongoing transition to renewable energy supply comes with a restructuring of power grids, changing their effective interaction topologies, more and more strongly decentralizing them and substantially modifying their input, output, and response characteristics. All of these changes imply that power grids become increasingly affected by collective, nonlinear dynamic phenomena, structurally and dynamically more distributed and less predictable in space and time, more heterogeneous in its building blocks, and as a consequence less centrally controllable. Here cornerstone aspects of data-driven and mathematical modeling of collective dynamical phenomena emerging in real and model power grid networks by combining theories from nonlinear dynamics, stochastic processes and statistical physics, anomalous statistics, optimization, and graph theory are reviewed. The mathematical background required for adequate modeling and analysis approaches is introduced, an overview of power system models is given, and a range of collective dynamical phenomena are focused on, including synchronization and phase locking, flow (re)routing, Braess’s paradox, geometric frustration, and spreading and localization of perturbations and cascading failures, as well as the nonequilibrium dynamics of power grids, where fluctuations play a pivotal role.

Description: Partial synchronization patterns play an important role in the functioning of neuronal networks, both in pathological and in healthy states. They include chimera states, which consist of spatially coexisting domains of coherent (synchronized) and incoherent (desynchronized) dynam- ics, and other complex patterns. In this perspective article we show that partial synchronization scenarios are governed by a delicate interplay of local dynamics and network topology. Our focus is in particular on applications of brain dynamics like unihemispheric sleep and epileptic seizure.

Description: For light-duty vehicles (LDVs), alternative powertrains and liquid fuels based on renewable electricity are competing options considered by policymakers and stakeholders for achieving necessary CO2 emission reductions in the transport sector. While the urgency of climate change and the need to reach mitigation targets are well understood, system-wide implications along other sustainability dimensions need further exploration. We integrate a detailed transport system model into an integrated assessment framework and couple it with prospective life cycle impact analysis. This allows to assess different technological pathways of the European LDV fleet until 2050 for a comprehensive set of environmental and resource depletion indicators. Results indicate that greenhouse gas emissions drop significantly in all mitigation scenarios. However, impacts increase in several non-climate change impact categories even with fully renewable electricity supply. Additional impacts arise from the production of battery and fuel-cell components, and from a significant rise in electricity demand, most prominently for synthetic fuels. We consequently find that changes in mobility life-styles and in the relevant industrial processes are paramount to reduce environmental impacts from a climate-friendly LDV fleet across all categories.

Description: This repository contains the source files for processing the datasets, running the analysis, and producing the plots for the following publication: Niklas H. Kitzmann, Pawel Romanczuk, Nico Wunderling and Jonathan F. Donges (2022). Detecting contagious spreading of urban innovations on the global city network. European Physical Journal Special Topics. DOI:10.1140/epjs/s11734-022-00470-4

Description: Climate change increasingly affects agricultural systems, making it necessary for farmers to adapt to changing climatic conditions. An important element shaping farmers’ adaptation decisions and their vulnerability is their respective land tenure system. Especially land tenure security can strongly influence farmers’ incentives for adapting to climate change. We review the literature to understand to what extent tenure security and other land tenure characteristics affect farmers’ ability to withstand climate change and how climate change is operationalised. 106 mostly peer-reviewed studies are examined using thematic network analysis and a network of interactions between land tenure and climate change in farming contexts is devised. The results show that three main interactions link land tenure systems and climate change with regard to agricultural livelihoods: (i) land tenure characteristics influence farmers’ adaptation uptake, type and intensity, (ii) certain tenure settings contribute to vulnerability of different socio-demographic groups in agricultural systems, e.g. women, migrants and indigenous communities, and (iii) the perception of tenure security itself is affected by climate change. Yet, the concept of tenure security is poorly defined in most studies, at times resulting in misleading conclusions and leaving important research gaps with regard to optimal land tenure incentives for farmers’ adaptation response. Climate change is often simplistically integrated into the assessments, without validation and analysis of longer term trends. None of the studies reviewed provides a comprehensive and systematic treatment of the multiple dimensions linking climate change and land tenure. Further exploration and empirical validation of the connection between land tenure and climate change in agricultural systems is thus warranted. This should include a more critical engagement with the exigencies of climate change response for agricultural systems, such as the need for flexible approaches to deal with climatic uncertainty. The results of this review are relevant for informing adaptation policy, where sustainable land governance has an integral role to play. Designing smart land tenure interventions based on improved understanding of (local) interactions between land tenure and climate can support farmers in effectively addressing the adverse effects of climate change.

Description: An equilibrium of a delay differential equation (DDE) is absolutely stable, if it is locally asymptotically stable for all delays. We present criteria for absolute stability of DDEs with discrete time-delays. In the case of a single delay, the absolute stability is shown to be equivalent to asymptotic stability for sufficiently large delays. Similarly, for multiple delays, the absolute stability is equivalent to asymptotic stability for hierarchically large delays. Additionally, we give necessary and sufficient conditions for a linear DDE to be hyperbolic for all delays. The latter conditions are crucial for determining whether a system can have stabilizing or destabilizing bifurcations by varying time delays.

Description: Despite the development of sophisticated statistical and dynamical climate models, a relative long-term and reliable prediction of the Indian summer monsoon rainfall (ISMR) has remained a challenging problem. Toward achieving this goal, here we construct a series of dynamical and physical climate networks based on the global near-surface air temperature field. We show that some characteristics of the directed and weighted climate networks can serve as efficient long-term predictors for ISMR forecasting. The developed prediction method produces a forecasting skill of 0.54 (Pearson correlation) with a 5-month lead time by using the previous calendar year’s data. The skill of our ISMR forecast is better than that of operational forecasts models, which have, however, quite a short lead time. We discuss the underlying mechanism of our predictor and associate it with network–ENSO and ENSO–monsoon connections. Moreover, our approach allows predicting the all-India rainfall, as well as the rainfall different homogeneous Indian regions, which is crucial for agriculture in India. We reveal that global warming affects the climate network by enhancing cross-equatorial teleconnections between the southwest Atlantic, the western part of the Indian Ocean, and the North Asia–Pacific region, with significant impacts on the precipitation in India. A stronger connection through the chain of the main atmospheric circulations patterns benefits the prediction of the amount of rainfall. We uncover a hotspot area in the midlatitude South Atlantic, which is the basis for our predictor, the southwest Atlantic subtropical index (SWAS index). Remarkably, the significant warming trend in this area yields an improvement of the prediction skill.

Description: COVID-19 has revealed how challenging it is to manage global, systemic and compounding crises. Like COVID-19, climate change impacts, and maladaptive responses to them, have potential to disrupt societies at multiple scales via networks of trade, finance, mobility and communication, and to impact hardest on the most vulnerable. However, these complex systems can also facilitate resilience if managed effectively. This review aims to distil lessons related to the transboundary management of systemic risks from the COVID-19 experience, to inform climate change policy and resilience building. Evidence from diverse fields is synthesised to illustrate the nature of systemic risks and our evolving understanding of resilience. We describe research methods that aim to capture systemic complexity to inform better management practices and increase resilience to crises. Finally, we recommend specific, practical actions for improving transboundary climate risk management and resilience building. These include mapping the direct, cross-border and cross-sectoral impacts of potential climate extremes, adopting adaptive risk management strategies that embrace heterogenous decision-making and uncertainty, and taking a broader approach to resilience which elevates human wellbeing, including societal and ecological resilience.

Description: This paper designs an event-triggering based communication strategy for the global attitude synchronization of a network of rigid bodies. To overcome the topological constraint on the manifold SO(3), the quaternion-based hybrid control strategy is designed using a binary logic variable, relying on the relative measurements of adjacent rigid bodies, to determine the torque orientation. The Zeno-free distributed event-triggering strategies (ETSs) are designed combining with the reset of the binary logic variable to generate discrete communication instants, where only the corresponding parts of the control inputs are updated at those discrete instants. By assuming perfect knowledge of the rigid bodies' dynamics and considering uncertainties and/or exogenous disturbances simultaneously, nominal and robust cases are analyzed to ensure the global attitude synchronization, respectively. The effectiveness of the main results is demonstrated by considering the attitude synchronization of six miniature quadrotor prototypes.

Description: This collection provides a contemporary excerpt of “Cities as complex systems”. The contributions have been submitted between April and October 2020. We briefly discuss example papers addressing the themes “urban scaling”, “urban mobility”, “flows in cities”, “spatial analysis”, “information technology and cities”, and “cities in time”. After motivating the intersection of cities and complexity, we provide an introduction and additional thoughts on urban scaling.

Description: With the prevalence of COVID-19, the modeling of epidemic propagation and its analyses have played a significant role in controlling epidemics. However, individual behaviors, in particular the self-protection and migration, which have a strong influence on epidemic propagation, were always neglected in previous studies. In this paper, we mainly propose two models from the individual and population perspectives. In the first individual model, we introduce the individual protection degree that effectively suppresses the epidemic level as a stochastic variable to the SIRS model. In the alternative population model, an open Markov queueing network is constructed to investigate the individual number of each epidemic state, and we present an evolving population network via the migration of people. Besides, stochastic methods are applied to analyze both models. In various simulations, the infected probability, the number of individuals in each state and its limited distribution are demonstrated.

Description: In industrial control systems, industrial infrastructure is often attacked by hackers. Due to the serious sample imbalance in industrial control data, the traditional machine learning method has poor performance in anomaly detection. In this paper, TrAdaboost algorithm is applied to industrial control anomaly detection. The samples that are easy to classify are taken as the source domain data, and the samples with poor classification effect are taken as the target domain. The source domain data is used to guide the target domain data training. Then, we improve the traditional TrAdaboost algorithm from two aspects of initial weight and final classifier, and apply it to industrial control anomaly detection. Finally, the performance of the algorithm on two different industrial control data sets is verified. And the improved algorithm is compared with other traditional algorithms. The experimental results show that the improved TrAdaboost algorithm has a significant advantage in predicting categories with a small sample size. This algorithm can accurately identify a few abnormal samples. Moreover, the F1 value, recall and precision value of the improved TrAdaboost algorithm on the two data sets have been significantly improved. This indicates that the improved TrAdaboost algorithm greatly improves the overall prediction accuracy of the model.

Description: To date, most regional and global hydrological models either ignore the representation of cropland or consider crop cultivation in a simplistic way or in abstract terms without any management practices. Yet, the water balance of cultivated areas is strongly influenced by applied management practices (e.g. planting, irrigation, fertilization, harvesting). The SWAT+ model represents agricultural land by default in a generic way where the start of the cropping season is driven by accumulated heat units. However, this approach does not work for tropical and sub-tropical regions such as the sub-Saharan Africa where crop growth dynamics are mainly controlled by rainfall rather than temperature. In this study, we present an approach on how to incorporate crop phenology using decision tables and global datasets of rainfed and irrigated croplands with the associated cropping calendar and fertilizer applications in a regional SWAT+ model for Northeast Africa. We evaluate the influence of the crop phenology representation on simulations of Leaf Area Index (LAI) and Evapotranspiration (ET) using LAI remote sensing data from Copernicus Global Land Service (CGLS) and WaPOR ET data respectively. Results show that a representation of crop phenology using global datasets leads to improved temporal patterns of LAI and ET simulations especially for regions with a single cropping cycle. However, for regions with multiple cropping seasons, global phenology datasets need to be complemented with local data or remote sensing data to capture additional cropping seasons. In addition, the improvement of the cropping season also helps to improve soil erosion estimates, as the timing of crop cover controls erosion rates in the model. With more realistic growing seasons, soil erosion is largely reduced for most agricultural Hydrologic Response Units (HRUs) which can be considered as a move towards substantial improvements over previous estimates. We conclude that regional and global hydrological models can benefit from improved representations of crop phenology and the associated management practices. Future work regarding the incorporation of multiple cropping seasons in global phenology data is needed to better represent cropping cycles in regional to global hydrological models.

Description: Land management practices can reduce the environmental impact of agricultural land use and production, improve productivity, and transform cropland into carbon sinks. In our study we assessed the biophysical and biogeochemical impacts and the potential contribution of cover crop practices to sustainable land use. We applied the process-based, global dynamic vegetation model LPJmL (Lund–Potsdam–Jena managed Land) V. 5.0-tillage-cc with a modified representation of cover crops to simulate the growth of grasses on cropland in periods between two consecutive main crops' growing seasons for near-past climate and land use conditions. We quantified simulated responses of agroecosystem components to cover crop cultivation in comparison to bare-soil fallowing practices on global cropland for a period of 50 years. For cover crops with tillage, we obtained annual global median soil carbon sequestration rates of 0.52 and 0.48 t C ha−1 yr−1 for the first and last decades of the entire simulation period, respectively. We found that cover crops with tillage reduced annual nitrogen leaching rates from cropland soils by medians of 39 % and 54 % but also the productivity of the following main crop by an average of 1.6 % and 2 % for the 2 analyzed decades. The largest reductions in productivity were found for rice and modestly lowered ones for maize and wheat, whereas the soybean yield revealed an almost homogenously positive response to cover crop practices replacing bare-soil fallow periods. The obtained simulation results of cover crop with tillage practices exhibit a good ability of the model version to reproduce observed effects reported in other studies. Further, the results suggest that having no tillage is a suitable complementary practice to cover crops, enhancing soil carbon sequestration and the reduction in nitrogen leaching, while reducing potential trade-offs with the main-crop productivity due to their impacts on soil nitrogen and water dynamics. The spatial heterogeneity of simulated impacts of cover crops on the variables assessed here was related to the time period since the introduction of the management practice as well as to environmental and agronomic conditions of the cropland. This study supports findings of other studies, highlighting the substantial potential contribution of cover crop practices to the sustainable development of arable production.

Description: The Mid-Brunhes Transition (MBT) refers to the change in the amplitude of glacial-interglacial cycles around 430 ka BP, with more pronounced, warmer interglacials after ca. 430 ka BP. Despite the advances in the understanding of glacial cycles, the cause and mechanism of the MBT are still not entirely clear. In this study we examine (i) whether the MBT is caused by a change in the intrinsic dynamics of glacial cycles and (ii) how important the systematic changes of the orbital elements across the MBT are for the occurrence of the MBT. In order to address these questions, we take a pure machine-learning approach. We develop an artificial neural network model which provides a skilful 21-ka ahead prediction of glacial-interglacial changes in the LR04 benthic δ18O stack record as well as a sea level reconstruction obtained by an inverse model. This allows us to predict the interglacial levels from glacial conditions. Although the neural network model is trained over a pre-MBT period of 900–450 ka BP, it exhibits the intensification of interglacials after 450 ka BP. This suggests that the dynamical characteristics generating the stronger post-MBT interglacials is inherent already before the MBT. When the neural network model is forced by a hypothetical insolation for which the amplitude of the obliquity cycles is kept at pre-MBT level, the MBT-like phenomenon does not appear in our simulations. In line with earlier suggestions, our results thus give quantitative evidence that the MBT is caused by amplitude changes of the obliquity forcing. For comparison, our results suggest that the change in the mean eccentricity level across the MBT has a smaller impact on the appearance of the MBT.

Description: 〈p〉On 17 March, Michal Meidan testified before the U.S.-China Economic & Security Review Commission on China’s Energy Plans and Practices. In her testimony, Michal discussed the outlook for China’s fossil fuel demand in China, the successes and challenges associated with fossil fuel supply and how this fits into the country’s low carbon energy transition. Michal […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/statement-before-the-u-s-china-economic-and-security-review-commission-policymaking-and-energy-supply-and-demand-in-chinas-domestic-economy/"〉Statement before the U.S.-China Economic and Security Review Commission: Policymaking and Energy Supply and Demand in China’s Domestic Economy〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: In this study, we provide a dynamical systems perspective to the modelling of pathological states induced by tumors or infection. A unified disease model is established using the innate immune system as the reference point. We propose a two-layer network model for carcinogenesis and sepsis based upon the interaction of parenchymal cells and immune cells via cytokines, and the co-evolutionary dynamics of parenchymal, immune cells, and cytokines. Our aim is to show that the complex cellular cooperation between parenchyma and stroma (immune layer) in the physiological and pathological case can be qualitatively and functionally described by a simple paradigmatic model of phase oscillators. By this, we explain carcinogenesis, tumor progression, and sepsis by destabilization of the healthy homeostatic state (frequency synchronized), and emergence of a pathological state (desynchronized or multifrequency cluster). The coupled dynamics of parenchymal cells (metabolism) and nonspecific immune cells (reaction of innate immune system) are represented by nodes of a duplex layer. The cytokine interaction is modeled by adaptive coupling weights between the nodes representing the immune cells (with fast adaptation time scale) and the parenchymal cells (slow adaptation time scale) and between the pairs of parenchymal and immune cells in the duplex network (fixed bidirectional coupling). Thereby, carcinogenesis, organ dysfunction in sepsis, and recurrence risk can be described in a correct functional context.

Description: The files contain MAgPIE 4.3.5 results of reduced wood harvest and forest protection scenarios. MAgPIE requires GAMS (https://www.gams.com/) including licenses for the solvers CONOPT and (optionally) CPLEX for its core calculations. As the model benefits significantly from recent improvements in GAMS and CONOPT4 it is recommended to work with the most recent versions of both. The results of the model run here have been cleaned up to avoid bulky uploads. The fulldata.gdx is the technical output of the GAMS optimization and contains all quantities that were used during the optimization in unchanged form. The mif-file is a CSV file of a specific format and is synthetized from the fulldata.gdx by post-processing scripts. It can be read in any text editor or spreadsheet program and is well suited for a brief look at the results and for further analysis.

Description: We consider trends in the m seasonal subrecords of a record. To determine the statistical significance of the m trends, one usually determines the p value of each season either numerically or analytically and compares it with a significance level α~. We show in great detail for short- and long-term persistent records that this procedure, which is standard in climate science, is inadequate since it produces too many false positives (false discoveries). We specify, on the basis of the family wise error rate and by adapting ideas from multiple testing correction approaches, how the procedure must be changed to obtain more suitable significance criteria for the m trends. Our analysis is valid for data with all kinds of persistence. Specifically for long-term persistent data, we derive simple analytical expressions for the quantities of interest, which allow to determine easily the statistical significance of a trend in a seasonal record. As an application, we focus on 17 Antarctic station data. We show that only four trends in the seasonal temperature data are outside the bounds of natural variability, in marked contrast to earlier conclusions.

Description: 〈p〉In 2021, China experienced several episodes of power shortages and outages, heightening already existing concerns about energy security. In response, the government instituted a rapid succession of market reforms and other regulatory changes, which have pushed the majority of power users into the power market and also allowed for a wider range of electricity prices. […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-podcast-chinas-power-market-reforms-in-an-age-of-insecurity/"〉Oxford Energy Podcast – China’s power market reforms in an age of insecurity〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-136-–-Chinas-power-market-reforms-in-an-age-of-insecurity.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-136-–-Chinas-power-market-reforms-in-an-age-of-insecurity.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉The dramatic rise in European, and indeed in global, gas prices over the summer of 2021, leading to unprecedented prices in Q4, has been the subject of much debate. Is it simply a market reflection of stronger than expected demand and weaker than expected supplies? Or is it a step change in the context of […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/a-series-of-unfortunate-events-explaining-european-gas-prices-in-2021-the-role-of-the-traded-gas-hubs/"〉A Series of Unfortunate Events – Explaining European Gas Prices in 2021: The role of the traded gas hubs〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉In this OIES podcast James Henderson talks to Anouk Honoré and Jack Sharples about the EU plan to diversify gas imports away from Russia in 2022. They discuss the latest strategy published by the European Commission on March 8, which addresses both the supply and demand-side options. The podcast considers the potential to import an […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oxford-energy-podcast-eu-plans-to-reduce-russian-gas-imports/"〉Oxford Energy Podcast – EU plans to reduce Russian gas imports〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-137-EU-plans-to-reduce-Russian-gas-imports-.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/03/Podcast-137-EU-plans-to-reduce-Russian-gas-imports-.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉India has been implementing climate actions since 2001, when it was one of very few countries to pass an Energy Conservation Act, followed by an industrial emissions trading scheme to force large manufacturing companies to become more energy efficient. A National Action Plan for Climate Change (NAPCC) was passed in 2008, and included relatively modest […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/indias-progress-on-its-climate-action-plan-an-update-in-early-2022/"〉India’s Progress on its Climate Action Plan – An Update in Early 2022〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉Russia’s invasion of Ukraine has catalysed a chorus of dismay and outrage from western companies with investments in Russia and has led some to announce their withdrawal from the country. Furthermore, it has also caused the US and the EU to impose sanctions on individuals and companies involved in the energy sector and to announce […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/thoughts-on-the-impact-of-foreign-companies-exiting-the-russian-oil-and-gas-industry/"〉Thoughts on the impact of foreign companies exiting the Russian oil and gas industry〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉On February 4 2022 China’s President Xi Jinping and Russia’s President Vladimir Putin signed a series of new oil and gas contracts including an additional 10 bcma gas pipeline deal. This comment reviews how the new gas deal between Russia and China fits into their strategies, highlights the key implications of expanded gas cooperation between […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/russia-and-china-expand-their-gas-deal-key-implications/"〉Russia and China Expand Their Gas Deal: Key Implications〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉This new OIES presentation features a comprehensive empirical assessment of the implications of the Ukraine war on oil price and supply/demand dynamics via a number of forecast scenarios examining the size of disruption in Russian supplies, OPEC and non-OPEC supply response, the impact of the latest US announcement of SPR release and other uncertainty scenarios. […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/russias-invasion-of-ukraine-and-global-oil-market-scenarios/"〉Russia’s invasion of Ukraine and global oil market scenarios〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉Brent is the world’s most important crude oil benchmark. Arguably, it is responsible for pricing almost seventy percent of globally traded crude oil and long-term LNG. Over time however, the falling production of Brent has forced the price reporting agencies (PRAs) to introduce new grades in the ‘basket’ of crudes eligible for delivery as ‘Brent’ […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/the-future-of-the-brent-oil-benchmark-a-radical-makeover/"〉The Future of the Brent Oil Benchmark: A Radical Makeover〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: Precursor signals for bifurcation-induced critical transitions have recently gained interest across many research fields. Common indicators, including variance and autocorrelation increases, rely on the dynamical system being driven by white noise. Here, we show that these metrics raise false alarms for systems driven by time-correlated noise, if the autocorrelation of the noise process increases with time. We introduce a new indicator for systems driven by non-stationary short-term memory noise, and show that this indicator performs well in situations where the classical methods fail.

Description: 〈p〉In this first of a new series of podcasts, OIES presents a regular review of the impact of the Russia-Ukraine war on energy markets. James Henderson interviews Mike Fulwood and Jack Sharples on the drivers of current price dynamics, the situation with Russian gas flows to Europe, the availability of LNG supply to Europe and […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oies-podcast-series-russia-ukraine-conflict-impact-on-energy-markets/"〉OIES Podcast Series: Russia-Ukraine War – Impact on Energy Markets〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/04/OIES-Podcast-Series-Russia-Ukraine-Conflict-–-Impact-on-Energy-Markets-1.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/04/OIES-Podcast-Series-Russia-Ukraine-Conflict-–-Impact-on-Energy-Markets-1.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉On 31 March 2022, President Putin signed a Decree on the Special Procedure for the Fulfilment by Foreign Buyers of Obligations to Russian Natural Gas Suppliers, which, in essence, requires buyers from ‘unfriendly’ countries to pay in roubles for gas delivered to them after 1 April 2022. The key objective of this comment is to discuss […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/rouble-gas-payment-mechanism-implications-for-gas-supply-contracts/"〉Rouble gas payment mechanism: implications for gas supply contracts〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉〈em〉〈span〉The focus of this research is to distinguish between shifting land-use patterns and their geo-environmental implications in Simhadripuram Mandal, YSR Kadapa district, Andhra Pradesh, India. While the terms Landuse and Landcover (LULC) are sometimes used interchangeably, they have distinct natural meanings. Landuse refers to the function of a piece of land, such as mining, agriculture, or habitation. Landcover refers to the ground's surface cover, which might include vegetation, water, barren soil, and so on. Landuse is a notion that has a lot of qualities. It refers to people's actions on land that are directly related to the land. Landcover, on the other hand, refers to the vegetation that covers the surface of the land. The changes in LULC in Simhadripuram Mandal during the last ten years were studied using satellite imageries. LULC changes have been mapped using remote sensing and GIS modeling. The study is characterized in to five classifications, they are vegetation, fallow land, barren land, waterbodies, and built-up-land. The results reveal from 2009–10 to 2019–20, waterbodies are slightly increased from 2010 to 2020, is 9.29 km〈sup〉2〈/sup〉. Vegetation is increased positively for the past decade to 25.16 Km〈sup〉2〈/sup〉. The unirrigated land has been decreased to 27.1 km〈sup〉2〈/sup〉. Built-up-land is increased from the last decade; it is noted as 22.77 km〈sup〉2〈/sup〉. Fallow land has been decreased to 30.12 km〈sup〉2〈/sup〉.〈/span〉〈/em〉〈/p〉

Description: 〈p〉〈em〉B〈/em〉〈em〉iodiversity, or the vast diversity of life on Earth, is rapidly vanishing. In the last few decades, there has been a massive loss. Several animal and plant species have declined in recent decades. At an alarming rate, hundreds of thousands of acres of forests have been devastated. Several blue whales, polar bears, pandas, and other well-known animals starved to death. Many yet-to-be-discovered species are also in jeopardy. In recent years, there has been a significant decrease in the number of forests. Surviving species on the planet have a wide range of options for living in diverse settings, each with its own set of behaviors. So, biodiversity is crucial for us. We must preserve it. Humans should find ways to restore balance to our environment. We've identified several contributing factors to the decline in biodiversity, which we can divide into five categories: - land and sea use, pollution, overexploitation of species, changes in the climate, and diseases caused by invasive species. Conservation of diversity is a method for preserving species richness, species diversity, habitat diversity, ecological diversity, and genetic diversity. It maintains our health, prosperity, food, fuel, and services. It shows its vitality in supporting many aspects of development. Here are some innovative and creative ways to aid in the fight against biodiversity loss.〈/em〉〈/p〉

Description: 〈p〉The gas market in Europe is in a state of real uncertainty as to whether Russia will cut off gas supplies to Europe, or whether the EU should sanction imports of gas on the grounds that their payments are fuelling the Russian war machine in Ukraine. The current situation of uncertainty and not knowing whether […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/russian-gas-to-the-eu-to-sanction-or-not-to-sanction/"〉Russian gas to the EU: to sanction or not to sanction〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: While carbon taxes are generally seen as a rational policy response to climate change, knowledge about their performance from an ex-post perspective is still limited. This paper analyzes the emissions and cost impacts of the UK CPS, a carbon tax levied on all fossil-fired power plants. To overcome the problem of a missing control group, we propose a policy evaluation approach which leverages economic theory and machine learning for counterfactual prediction. Our results indicate that in the period 2013–2016 the CPS lowered emissions by 6.2 percent at an average cost of €18 per ton. We find substantial temporal heterogeneity in tax-induced impacts which stems from variation in relative fuel prices. An important implication for climate policy is that whether a higher carbon tax leads to higher emissions reductions and higher costs depends on relative fuel prices.

Description: 〈p〉This month’s Special Issue continues to assess the implications of the Ukraine war on our short-term oil market outlook for supply/demand and price dynamics to 2023, featuring the first detailed assessment of the impacts on OECD products demand. The analysis considers two principal scenarios. A Reference case in which self-sanctioning measures and obstacles in redirecting Russian crude and petroleum […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oies-oil-monthly-issue-13/"〉OIES Oil Monthly – Issue 13〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉

Description: 〈p〉In this latest OIES podcast we continue our weekly updates of the impact of the war between Russia and Ukraine on energy markets. This week we review the significant increase in global LNG supply and its availability to the European market, while also considering the other sources of non-Russian supply. We also review the flows […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oies-podcast-series-impact-of-russia-ukraine-war-on-energy-markets-2/"〉OIES Podcast – Impact of Russia-Ukraine War on Energy Markets Series – 2〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/04/OIES-Podcast-Series-Impact-of-Russia-Ukraine-War-on-Energy-Markets-2.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/04/OIES-Podcast-Series-Impact-of-Russia-Ukraine-War-on-Energy-Markets-2.mp3"〉💾〈/a〉〈/p〉〈/div〉

Description: 〈p〉Brent is the world’s most important crude oil benchmark. However, the falling production of Brent has forced the price reporting agencies to introduce new grades in the ‘basket’ of crudes eligible for delivery as ‘Brent’ and widen the loading dates that can be used in their assessments. Brent has become just a brand name in […]〈/p〉 〈p〉The post 〈a rel="nofollow" href="https://www.oxfordenergy.org/publications/oies-podcast-the-future-of-the-brent-oil-benchmark-a-radical-makeover/"〉OIES Podcast – The Future of the Brent Oil Benchmark: A Radical Makeover〈/a〉 appeared first on 〈a rel="nofollow" href="https://www.oxfordenergy.org/"〉Oxford Institute for Energy Studies〈/a〉.〈/p〉 〈div class="enclosure"〉〈p class="enclosure-content"〉〈audio preload="none" src="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/04/PODCAST-140-Future-of-the-Brent-Benchmark.mp3" controls="controls"〉〈/audio〉 〈a download="" href="https://a9w7k6q9.stackpathcdn.com/wpcms/wp-content/uploads/2022/04/PODCAST-140-Future-of-the-Brent-Benchmark.mp3"〉💾〈/a〉〈/p〉〈/div〉