Analysis of trends in the development of cities’ heat supply systems

New challenges—including the modern urban development policy, formation of the market of energy efficient technologies and different types of equipment of a broad power capacity range, tightening requirements to reliability, quality, and economic accessibility of heat supply—enhance the competitiveness of decentralized heat supply. In addition, its spontaneous growth and not always reasonable implementation lead to unjustified expenses, low efficiency, and ecological inconsistency. This proves the relevance of solving the problems of dividing an urban territory into zones of centralized heating (CH) and decentralized heating (DCH) along with their planning and justification, as well as determining a reasonable level of heat supply centralization and concentration of heat sources' power capacity. Solving these problems using the suggested method will allow optimizing the application areas for various types of heat supply and heat sources, justifying the degree of heat power capacity concentration and the extent of the systems as early as at the phase of a detailed urban planning project and then refining them during the design of urban heat supply systems. This will dramatically improve the reasonability of the decisions made and will simplify the procedure of their implementation. For criteria of limiting the extent (radius) of heat supply systems and defining their type, we suggest using standard values—the density of heat load per unit length of the pipeline and per unit area of urban territory. Standard values must be differentiated across the territory of Russia taking into account regional climatic and economic conditions and unique characteristics of heat supply development in cities and towns. The present article continues and develops the statements made in the previous articles created within the framework of the Theory of Hydraulic Circuits and takes into account the current situation and emerging trends in heat supply.     

What’s next for Cuba’s electricity sector?

Cuba’s electric sector is approaching an inflection point. Although the country has historically relied upon non-commercial barter agreements for imported oil to meet its electric demand, a combination of factors including reducing imports, increasing demand, and ambitious climate change goals suggest new pathways forward may be warranted. The way Cuba responds to near- and long-term challenges will help set the stage for its energy future. This article describes Cuba's electric sector and provides a set of key recommendations to consider going forward.     

Electricity in the 1970’s,Water in the 2020’s

This articles discusses the parallels between the past trends in the US electricity sector with forthcoming trends in the water sector.     

On the radicality of New York’s Reforming the Energy Vision

In his article ‘The REVolution Yields to a More Familiar Path,’ Dr. Makholm argues that the New York commission’s REV efforts are misguided because the traditional regulatory framework is efficient and well developed. Looking to the entire set of REV dockets, this article argues that the REV is attempting to overcome deeply entrenched incumbency advantages and is therefore both ‘radical’ and necessary to the successful transition to a clean, distributed energy infrastructure.     

A study of within-subject reliability of the brain’s default-mode network

Objective

Resting-state functional magnetic resonance imaging (fMRI) is promising for Alzheimer’s disease (AD). This study aimed to examine short-term reliability of the default-mode network (DMN), one of the main haemodynamic patterns of the brain.

Materials and methods

Using a 1.5 T Philips Achieva scanner, two consecutive resting-state fMRI runs were acquired on 69 healthy adults, 62 patients with mild cognitive impairment (MCI) due to AD, and 28 patients with AD dementia. The anterior and posterior DMN and, as control, the visual-processing network (VPN) were computed using two different methodologies: connectivity of predetermined seeds (theory-driven) and dual regression (data-driven). Divergence and convergence in network strength and topography were calculated with paired t tests, global correlation coefficients, voxel-based correlation maps, and indices of reliability.

Results

No topographical differences were found in any of the networks. High correlations and reliability were found in the posterior DMN of healthy adults and MCI patients. Lower reliability was found in the anterior DMN and in the VPN, and in the posterior DMN of dementia patients.

Discussion

Strength and topography of the posterior DMN appear relatively stable and reliable over a short-term period of acquisition but with some degree of variability across clinical samples.

     

How may a generator manage the risk of PJM’s incentive scheme for capacity delivery?

Motivated by PJM’s recently proposed incentive scheme for capacity delivery during system emergencies, this paper develops two wholesale market products that a generator may use to manage the scheme’s risk. The first product is an insurance that removes the scheme’s downside risk due to the penalty for under-delivery. The second product is a forward contract that insulates a generator from the scheme’s risk due to the penalty for under-delivery and reward for over-delivery. The paper’s main contribution is how to price these newly developed products using readily available data.     

Analysis of a thermal generator’s participation in the Western Energy Imbalance Market and the resulting effects on overall performance and emissions

The inception of the Western Energy Imbalance Market (EIM) in November of 2014 has had significant impacts on participating balancing authorities (BAs) and individual generators. The EIM serves to balance available energy across a large geographical footprint. Since the market’s creation, the California Independent System Operator (CAISO) has reported that many benefits have been realized by participating BAs, including savings of $502 million and the avoided curtailment of an estimated 734,000 MWh of energy produced by variable renewable energy (VRE). Balancing energy across a larger geographic footprint, in conjunction with other factors (e.g., fluctuating fuel prices, new environmental policies), has also resulted in significant changes in the operation of some thermal generating stations which have traditionally operated as baseload units. The effects of these new operating practices on baseload units have not been characterized. This study analyzes the detailed operational history of a single coal-fired thermal generating station experiencing a large degree of load flexing located within the footprint of the EIM. A dataset comprised of hourly operational data from two and one-half years before and after beginning market participation was analyzed. Changes in operating practices, unit performance, and emission rates from this unit between the two periods were identified from this analysis. It was observed that the operational range of the unit has expanded by 65% and the unit has experienced ramping situations approximately 4.6 times more often since entering the EIM. Continual load changes have contributed to 18 times more turbine cycles, the impact of which on unit health and longevity cannot be fully characterized. The unit has demonstrated a strong adaptive ability in altering operational practices to meet the needs of the new market. Primarily due to lower average load operation, overall efficiency has decreased by 2.7%.     

Insuring the penalty risk of non-delivery in the United Kingdom’s capacity market

In July 2021, the United Kingdom (UK) Government considered tripling the UK grid’s performance-based incentive scheme’s penalty for capacity non-delivery during a shortage. This paper proposes an insurance that a generator may buy to manage its risk exposure to the scheme’s penalty. It also shows how to use readily available data to calculate the insurance’s per MW premium. These findings suggest that the proposed insurance deserves consideration by generators and insurance sellers.     

The concept of new-generation steam turbines for the coal power engineering of Russia. Part 2. Substantiating the long-term strength of the steam turbine’s high-temperature rotors

The possibility of constructing a K-660-30 two-cylinder steam turbine for ultrasupercritical steam conditions with reheating, the concept of which was described in the first part of this paper, is substantiated. It is shown that this turbine can be constructed using the available heat-resistant materials.     

Magnetization transfer for the assessment of bowel fibrosis in patients with Crohn’s disease: initial experience

Object

To assess the feasibility of magnetization transfer (MT) imaging of the bowel wall in patients with Crohn’s disease (CD), and to evaluate its utility for the detection of intestinal fibrosis.

Materials and methods

In this prospective study, 31 patients (age 39.0 ± 13.2 years) with CD were examined in a 1.5T MR scanner. To establish a standard of reference, two independent readers classified the patients in different disease states using standard MR enterography, available clinical data and histological findings. In addition to the standard protocol, a 2D gradient-echo sequence (TR/TE 32 ms/2.17 ms; flip angle 25°) with/without 1,100 Hz off-resonance prepulse was applied. MT ratios (MTR) of the small bowel wall were computed off-line on a pixel-by-pixel basis.

Results

The MT sequences acquired images of sufficient quality and spatial resolution for the evaluation of the small bowel wall without detrimental motion artefacts. In normal bowel wall segments, an intermediate MTR of 25.4 ± 3.4 % was measured. The MTR was significantly increased in bowel wall segments with fibrotic scarring (35.3 ± 4.0 %, p < 0.0001). In segments with acute inflammation, the mean MTR was slightly smaller (22.9 ± 2.2 %).

Conclusion

MT imaging of the small bowel wall is feasible in humans with sufficient image quality and may help with the identification of fibrotic scarring in patients with CD.     

FERC’s Flawed Assessment of the Benefits and Costs of Regional Transmission Organizations

FERC’s Economic Assessment does not meet the minimal requirements of a cost–benefit analysis of RTOs. It fails to address critical incentive questions associated with the RTO structure, and begs the question of whether RTOs will in fact make electricity markets more competitive and efficient.     

Identification of parameters of models of electric network elements on the basis of Tellegen’s theorem

An evaluation criterion of the permissibility of using the parameters of a model to identify modes of electric network elements with consideration for the constancy of parameters being identified and the error of results based on Tellegen’s theorem is presented. Calculating formulas of proposed criterion for various elements of an electric power system are developed. The proposed criterion makes it possible to detect the presence of distorted information and evaluate the identification error.     

Investigation of the ambient temperature effects on transformer’s insulation life

The insulation hot spot temperature (HST) represents the most important limiting factor of a transformer insulation life. Ambient temperature involved in the HST computations in all transformer thermal models affects insulation life-time directly or indirectly. Regarding the importance of the ambient temperature in transformer’s insulation life, in this paper a new thermal model for the estimation of HST in transformers has been proposed and using this thermal model, the effect of the ambient temperature on HST and transformer insulation life is investigated. The proposed model has been validated using real data gathered from a 180 MVA transformer.     

Future Expectation for China’s Nuclear Power

China: the future of nuclear powerWang Yonggan: In terms of the highlighted issue ofenergy security, oil is of paramount importance, coal isthe foundation and electricity is the pivot according to     

Firsts of steam generator unit in the history of new China’s power industry

Unit eaPaeity(MW) 6 12 25 25 50 50100100125200300300300300330500600600600800900Name ofPowerPlant Tianj扭、nP.R Chongqing_P.R Fuxin P.P, ZhabeiP.P. FushunP.P. Zhabel P.P. JilinC卫. 一Ga匀ing P.P. wujinzP.P._ ChaoyangP.P. wangting只P. 饰omengP.R Yuanbaoshan RP shihengP卫、 Dalate P.P一 ShentouNo.2 P.P‘ PingweiP.P.一、勺anbaoshanP.只、HarbinNo.3 P.P一 SuizhongP、P.叭厄igaoqiaoN。念G.C.Ndte.’ P.P.一PowerP白n心CP.一山g‘nerationP勿nt,’ G.C一GenerationCo刀切anyFirsts …     

Analysis of renewable energy projects’ implementation in Russia

With the enactment in 2013 of a renewable energy scheme by contracting qualified power generation facilities working on renewable energy sources (RES), the process of construction and connection of such facilities to the Federal Grid Company has intensified in Russia. In 2013–2015, 93 projects of solar, wind, and small hydropower energy were selected on the basis of competitive bidding in the country with the purpose of subsequent support. Despite some technical and organizational problems and a time delay of some RES projects, in 2014–2015 five solar generating facilities with total capacity of 50 MW were commissioned, including 30 MW in Orenburg oblast. However, the proportion of successful projects is low and amounts to approximately 30% of the total number of announced projects. The purpose of this paper is to analyze the experience of implementation of renewable energy projects that passed through a competitive selection and gained the right to get a partial compensation for the construction and commissioning costs of RES generating facilities in the electric power wholesale market zone. The informational background for the study is corporate reports of project promoters, analytical and information materials of the Association NP Market Council, and legal documents for the development of renewable energy. The methodological base of the study is a theory of learning curves that assumes that cost savings in the production of high-tech products depends on the production growth rate (economy of scale) and gaining manufacturing experience (learning by doing). The study has identified factors that have a positive and a negative impact on the implementation of RES projects. Improvement of promotion measures in the renewable energy development in Russia corresponding to the current socio-economic situation is proposed.     

Evaluation of the Moderately Leading Development in China’s Electric Power Industry

This article analyzes the importance of the moderately leading development in electric power industry, and the basic policy of the industry in China. It evaluates if the industry is appropriately developed ahead of other industries from the aspects of legal structuring, planning, electricity pricing mechanism, fixed assets investment, human resources, technological innovation and production and supply capacity etc., and proposes f ive recommendations.     

Ampere’s law in the calculation of ponderomotive forces in current loops

Comparison of two forms of Ampere’s law shows that the symmetrized version is no longer useful.     

Comparison of two methods for magnetic field synthesis on a solenoid’s axis

Magnetic field synthesis problems have been discussed at length in scientific literature but they still remain as a topic of research in electrical engineering, physics and medical applications. In these disciplines, there is often a need to design an electromagnetic arrangement which can generate a magnetic field of required distribution. Such an arrangement can also work as an active shield. The aim of an active shield is to generate a specified magnetic field which counteracts the external magnetic fields in a protected region. The idea of active shielding is to construct a suitable arrangement of coils, excited with currents that generate an opposite magnetic field sufficient to cancel out the unwanted external fields. The opposite field must have the same frequency and amplitude as the external field. If the incident field presents a wide bandwidth, the final aim is to generate an opposite field in the same frequency range or at least in a range as large as possible. Two independent methods of magnetic fields synthesis, i.e. iteratively regularized Gauss–Newton method and Genetic Algorithm coupled with Bezier curves-based method, are discussed and compared in this paper.