Full Year Of Operation Research Articles

An object-oriented implementation of a recursive “quantum network” solver and its application to district heating networks

With the increasing importance of energy efficiency and sustainability, the demand for high-performance district heating networks is also on the rise. As traditional engineering methods were often no longer sufficient, several packages for numerical simulation have evolved. Many of them offer high accuracy at the cost of considerable manual preparation and computational effort. However, there is still no user-friendly software that is equally suitable for simplified studies in the early project phase, for the rapid optimisation of multiple concepts and for subsequent detailed planning and dimensioning. For this reason and in cooperation with some companies from the energy sector, we had conceived a novel, highly flexible modular approach, the so-called “quantum networks”, where all parts of the district heating network are appropriately abstracted into quantum elements. Now we present our recent implementation of this model in an object-oriented C++ library. Starting from a generalised base class and making use of the concepts of inheritance and polymorphism, the idea of different levels of detail for the same element type is directly realised and can always be further refined. In addition, as all elements are derived from the same base class, they all share the same outer appearance and can thus be easily combined or interchanged. Based on these prerequisites, a dedicated thermo-hydraulic solver has then been developed. Thanks to its recursive design requiring neither outer iterations nor matrix inversions, it proves to be extremely fast and is therefore suitable for rapid design or optimisation studies in which a vast number of configurations has to be computed. To conclude this part of the work, the developed C++ library was benchmarked on two use cases covering a full year of operation that can now be computed in approximately one second of runtime.

An Adaptive Battery Charging Method for the Electrification of Diesel or CNG Buses as In-Motion-Charging Trolleybuses

The decarbonization of urban bus fleets can be made by their electrification as In-Motion-Charging (IMC) buses which can run both as trolleybuses or in battery-mode. The benefit is that IMC buses can use the existing trolleygrid infrastructure where their route overlaps with it to charge the battery, and operate in battery-mode outside of it. Presently, the IMC battery charging power is set conservatively to the minimum of all the spare capacities of the traction substations found along the bus route. This can render most electrification projects techno/economically infeasible as not enough energy is picked up for the battery-mode operation and long charging times at bus terminals are required. This paper proposes then an Adaptive Charging approach that uses the locally available spare capacity under any traction substation, taking into account the limitations of the maximum substation power and the minimum line voltage. The method is proven here both theoretically and in a case study over one full year of operation of four electrified diesel/CNG bus lines in Arnhem, the Netherlands, using comprehensive and verified trolleybus and trolleygrid models. The proposed Adaptive Charging method, as opposed to the present conservative method (here, Regular Charging), is shown to make one bus electrification project completely feasible, and reduce the extra terminal charging time for the other lines by up to 64%.

Using large, open datasets to understand spatial and temporal patterns in lotic ecosystems: NEON case studies

AbstractLeveraging big, open data is the next frontier in ecology. The National Ecological Observatory Network (NEON) is a network of monitoring sites collecting ecological data from across the United States. Using a case study approach, we provide examples of how NEON data can be applied to address a few big questions in aquatic ecology. First, we examined spatial patterns in stream water chemistry, to determine whether sites tend to cluster into regions based on geographic proximity. We found that this was not the case, likely because the hydrologic, geologic, and anthropogenic factors that drive heterogeneity in stream water chemistry vary across smaller spatial scales. Second, we examined temporal variability in stream water chemistry. We determined that the majority of catchments are relatively chemostatic (i.e., discharge varies by orders of magnitude more than concentrations) and that differences between catchments are likely to shift across decades due to changes in network conductivity. Third, we tested predictions of the River Continuum Concept (RCC) along a gradient from a second‐order stream to a seventh‐order river. We found that longitudinal patterns in metabolism, carbon chemistry, and macroinvertebrate community composition generally follow the patterns predicted by the RCC. NEON is only in its third year of full operations, with a planned 30‐year life. The studies presented here show the utility of NEON data, while only using a subset of the many data products that NEON produces. The massive amounts and types of data NEON generates, in conjunction with other national‐scale datasets, will allow the research community to better understand how aquatic ecosystems function and respond to drivers of long‐term change.

On-Orbit Calibration and Performance of NOAA-20 VIIRS Reflective Solar Bands

The NOAA-20 (N20) satellite was launched on November 18, 2017 carrying the second Visible Infrared Imaging Radiometer Suite (VIIRS) instrument. Immediately following the launch, the VIIRS passed a series of intensive calibration and validation tests, after which regular calibration and operation activities have continued successfully for more than three years. The production of NASA Collection 2 Level 1B (C2 L1B) for N20 VIIRS began in summer 2019. In this article, we evaluate the early mission performance of the N20 VIIRS reflective solar bands (RSB) covering the first three full years of operation. The calibrated RSB gains are calculated primarily from the onboard solar diffuser (SD) and used in generating the C2 L1B reflectance and radiance products. We also show the on-orbit performance of the instrument noise, signal-to-noise ratio (SNR), and a reflectance uncertainty assessment. Comparisons are made to the first three years of operation of the first VIIRS instrument, aboard the Suomi National Polar-orbiting Partnership (SNPP) satellite. We evaluate the long-term stability of the calibrated N20 RSB reflectance product by looking at the long-term trends of lunar observations and data from the pseudo-invariant Libya 4 desert site. The N20 RSB have had excellent early mission performance, with changes in the gain of less than 0.5% in the first three years across all detectors, stable L1B reflectance, and very stable values of detector SNR and reflectance uncertainty.

Evaluation of Transportation Infrastructure: A Case Study of Gold Coast Light Rail Stage 1&2

Since the COVID-19 pandemic began, there has been increased reliance on new infrastructure projects to counter economic fallout and underpin employment security. Urban and inter-urban transportation projects, such as major road, rail and port facilities, are popular choices for national and state governments in Australia as they provide broad fiscal support across all sectors of the economy. The problem with stimulus is making sure that the quality of the new infrastructure provides collective utility to a community or region. Whether the benefits will be worthwhile and represent best use of resource inputs requires financial, social, ethical and environmental consequences to be evaluated in a comparable format. The aim in this paper is to analyse the Gold Coast Light Rail (GCLR) Stage 1&2 project using a method that is capable of merging tangible and intangible criteria using an ordinal ranking algorithm. While the GCLR case study is undertaken with the benefit of hindsight, normally these types of evaluations are performed in real time as a project progresses from initiation (design) to implementation (deliver) and influence (delight). The method adopted in this study represents a modern form of multi-criteria decision-making, which enables successful projects to be distinguished from unsuccessful ones using a time period from commencement until one full year of operation has occurred. The i3d3 model, developed by a team from Bond University, has the unique benefit of ranking projects from best to worst across an organisational portfolio, geographic region or industry sector. It also supports past project performance to inform new design through application of a continuous improvement process of recording lessons learned. The GCLR case study calculated 100% of the critical success factors in the model to be positive and produced an overall success ranking of 23 (on a scale of -100 to +100). This paper presents the approach taken to evaluate GCLR’s level of success and the calculations that took place to reach this finding. This is the first time i3d3 has been used on an Australian project.

Exploring the Benefits of Photovoltaic Non-Optimal Orientations in Buildings

As solar photovoltaics in buildings reaches maturity, grid integration and economic yield are topics of greater interest. The traditional design of photovoltaic installations has considered the optimal orientation of photovoltaic modules to be that which yields the maximum annual energy production. The influence of the consumption patterns and the hourly variable electricity prices implies that this traditional optimal design might not be the most profitable. Using a full-year dataset for a residential installation, alternative installations using canopies and modules attached to the façades are simulated. By evaluating the energy balances for different annual consumptions, it is found that the canopy and façade installations offer better self-consumption of the PV produced energy, reflected in a 9% higher self-consumption degree using modules on façades and a 5% higher self-consumption degree using canopies. The economic evaluation under the new electricity tariffs in Spain shows a better profit for PV self-consumption, reducing the time of return on investment by more than 2 years. The analysis of different alternatives for an industrial PV allowed us to identify several benefits for these orientations which are confirmed after a full year of operation, such as an increase of up to 59% in annual energy production over the optimal-producing orientation.

Boundary Pass underwater listening station cabled hydrophone array system

An advanced cabled real-time underwater listening station was deployed in May 2020 in Boundary Pass, British Columbia, Canada, to measure underwater radiated noise of commercial vessels and to detect and track vocalizing marine mammals. This system was sponsored by Transport Canada and is operated jointly by Vancouver Fraser Port Authority and JASCO Applied Sciences (Canada) Ltd. The system consists of two synchronized tetrahedral hydrophone arrays, each with 1.65 m hydrophone spacings, deployed 300 m apart on the seabed in 190 m water depth. The hydrophone frames are connected to shore by two 2.8 km fiber-optic cables, and also support ADCP and CTD sensors, sound projectors for calibrations, and video cameras. The Boundary Pass location was chosen because of its relatively deep water and because the major inbound and outbound commercial shipping lanes leading to Vancouver become narrow and adjacent here, allowing acoustic measurements of ships passing in both directions. In this presentation we will discuss the system technical design and sensor specifications. We will also discuss its deployment and the data processing and presentation systems, with a brief overview of the substantial measurements obtained in the first full year of operation.

Impact of Check It: A Novel Community-Based Chlamydia Screening and Expedited Treatment Program for Young Black Men.

This study aimed to estimate the impact of the Check It program, a novel community-based chlamydia seek, test, and treat program for young Black men who have sex with women, on test positivity rates for chlamydia in young Black women. We used a synthetic control model to compare chlamydia test positivity rates in Orleans Parish (intervention site) with other similar parishes (control sites) in Louisiana. We estimated a model that used all other parishes as potential contributors to a synthetic control for Louisiana as well as a sample limited to the 40 parishes in Louisiana with the largest Black populations. The Check It program was associated with a 1.69-percentage-point decline in chlamydia positivity in the first full year of operation and a 2.44-percentage-point decline in chlamydia positivity in the second full year of operation compared with control sites with the largest Black populations (P = 0.05). Results were similar when the treatment site was compared with all other sites in Louisiana. The Check It program was associated with a significant decline in chlamydia testing positivity rates among women in Orleans Parish compared with control sites. Screening of young Black men who have sex with women can decrease rates in women living in the same community. Future recommendations for chlamydia screening of young men should be considered.

Analysis of PV Self-Consumption in Educational and Office Buildings in Spain

As grid parity is reached in many countries, photovoltaic self-consumption is raising great interest. Currently, there is a big number of new projects being developed in Spain thanks to the new regulation. From the experience of the monitoring of one full year of operation of a self-consumption PV plant in a university building, a regulatory, energy, and economic analysis is made for this type of building. It has been carried out by simulating the behavior of the building with installations within the range of PV powers allowed in the Spanish regulation. The analysis shows the good fitting between the new Royal Decree of Self-Consumption and the new Building Code. The economic analysis proves that the new simplified compensation method gives the best economic return for this use of the buildings when the PV production is matched with the consumption. The time of return of investment is between 8 and 9 years, and the levelized cost of electricity (LCOE) is into the range of the pool market price of electricity. These results show the profitability of PV self-consumption for this type of building.

Los Angeles Apparel: Locally Made in a Global Market

This case takes place during Los Angeles Apparel’s second full year of operation. Manufacturing fashion basics such as tee shirts and leggings, the company’s operations are located entirely in Los Angeles, eschewing the typical international apparel supply chains. The central figure in the case is founder and CEO Dov Charney. A nationally known figure, Charney was previously the founder and CEO of American Apparel, an apparel manufacturer and retailer, which at its peak reached annual sales in excess of $600 million and operated almost 300 stores across 20 countries. Charney’s controversial management style made him both famous and infamous and his tenure as CEO came to an end in 2014 when he was ousted by the company’s board. In 2016, Charney founded Los Angeles Apparel with a desire to recreate what he saw as the best aspects of American Apparel – local and ‘sweatshop free’ manufacturing. Following the same trajectory as the earlier company, Charney began by focusing on wholesale B2B channels. He had recently added a B2C ecommerce channel and was considering opening brick-and-mortar stores in the near future. But much had changed in the two decades since American Apparel’s initial success. Which path forward was best for Los Angeles Apparel in current environment?

Numerical model of vertical axis wind turbine performance in realistic gusty wind conditions

The goal of this study is to implement a numerical strategy to estimate the performance of a Vertical Axis Wind Turbine (VAWT) in response to realistic winds typical of an urban/suburban area over a full year of operation, and to predict the Levelized Cost of Energy (LCOE) produced by that VAWT in comparison to the national electricity price. Wind speed data from sensors located in Oklahoma City were used as input. Three numerical models were implemented, including Computational Fluid Dynamics (CFD), Blade Element Momentum (BEM), and a transient response model based on conservation of angular momentum of the VAWT. Here, CFD is utilized to simulate the flow around an isolated turbine blade in order to obtain the dynamic lift and drag coefficients as a function of azimuth angle, wind speed, and rotational speed. In total, 86 CFD simulations were performed over a range of wind speeds from 3 to 15 m/s and tip speed ratios from 2.5 to 4.5. These results are then used as input to the BEM and transient response models. Results show that the LCOE price for the VAWT is equal to or less than the average national electricity price at four locations where annual average wind speed measures ≥4.3 m/s.

Economic evaluation of the Melbourne Mobile Stroke Unit.

The Melbourne Mobile Stroke Unit (MSU) is the first Australian service to provide prehospital acute stroke treatment, including thrombolysis and facilitated triage for endovascular thrombectomy. To estimate the cost-effectiveness of the MSU during the first full year of operation compared with standard ambulance and hospital stroke care pathways (standard care). The costs and benefits of the Melbourne MSU were estimated using an economic simulation model. Operational costs and service utilization data were obtained from the MSU financial and patient tracking reports. The health benefits were estimated as disability-adjusted life years (DALYs) avoided using local data on reperfusion therapy and estimates from the published literature on their effectiveness. Costs were presented in Australian dollars. The robustness of results was assessed using multivariable (model inputs varied simultaneously: 10,000 Monte Carlo iterations) and various one-way sensitivity analyses. In 2018, the MSU was dispatched to 1244 patients during 200 days of operation. Overall, 167 patients were diagnosed with acute ischemic stroke, and 58 received thrombolysis, endovascular thrombectomy, or both. We estimated 27.94 DALYs avoided with earlier access to endovascular thrombectomy (95% confidence interval (CI) 15.30 to 35.93) and 16.90 DALYs avoided with improvements in access to thrombolysis (95% CI 9.05 to 24.68). The MSU was estimated to cost an additional $30,982 per DALY avoided (95% CI $21,142 to $47,517) compared to standard care. There is evidence that the introduction of MSU is cost-effective when compared with standard care due to earlier provision of reperfusion therapies.

Unlocking the potential of faster payments in the USA: An interview with Attila Csutak

Many Americans now have access to faster payments through Early Warning Services’ Zelle or through services provided by their financial institution that utilise the RTP network, the real-time payment system launched by The Clearing House in 2017. In this interview, Attila Csutak, Vice President and Product Manager of RTP and Zelle for KeyBank, shares insights into KeyBank’s first full year of operations with Zelle and the RTP network. He also discusses the current state of faster payments adoption in the USA, and offers observations on the potential impacts of real-time payments in the coming years.

Leachates From Landfill Sites In Thessaloniki, Greece: Effect Of Aging

Sanitary landfilling still is one of the most common management systems of solid urban wastes. The persistent environmental impact of landfills depends on leachate characteristics. The present study aimed at the characterisation of leachate from two landfill sites in the prefecture of Thessaloniki, Greece. Mavrorachi landfill stands in our study as a representative Greek active landfill site, that started operating in 2008. Tagarades landfill has stopped receiving waste from 2008 after 27 years of full operation. In this investigation, leachate samples were physico-chemically characterised so as to assess their pollution potential and their concentration in regard to the type and age of landfill. Elevated concentrations of inorganic and organic constituents were observed in the leachate composition. COD ranged from 2,490 mg/L to 19,700 mg/L, while the respective range for BOD was 390-14,850 mg/L during a 35-year period. The pH values of the leachate samples presented more moderate fluctuations between 7.3 and 8.5. In addition, the ammoniacal nitrogen content increased as landfill age increased, whereas heavy metals concentrations showed significant variations with a slight decreasing trend. The results presented in this paper proved that as time passed, the values of most parameters decreased as the biodegradable compounds are broken down while the refractory compounds resist to biodegradation. Thus, the age has a pronounced influence on the composition of leachate. This study also focused on quantifying the level of contamination that leachates can be potentially cause on a comparative basis by Leachate Pollution Index (LPI). LPI values showed that pollution load was declining but is still not negligible after 33 years.

“Solar fitness and wellness” – A unique design for sustainable wellness technologies

A spa facility with two saunas and a steam bath aiming at a primary energy demand reduction by a factor of 6 with reference to a conventional system was designed and built into the NEST innovation platform. For performance analysis, simulations over the course of a year were performed and calibrated with available measurement data. It was found that the efficiency goal along with the targeted annual net zero energy balance could be achieved. For an in-depth performance analysis in the future, a more stable operation and optimized control is needed along with measurement data for a full year of operation.

Performance evaluation of an industrial borehole thermal energy storage (BTES) project – Experiences from the first seven years of operation

Borehole thermal energy storage (BTES) is a technology which allows for both seasonal and short-to-medium-term storage of thermal energy and which can be used for both heating and cooling. This makes BTES of special interest to many industries. However, post-implementation evaluations of large-scale industrial BTES are scarce. The BTES at Xylem's production plant in Emmaboda, Sweden is one of the world's largest BTES systems for storage of industrial excess heat. In this paper, the BTES at Emmaboda was evaluated with respect to how it was integrated and how it has performed during its first seven years of operation. The BTES consists of 140 boreholes, 150 m deep, and heat for storage is mainly recovered from two high-temperature ovens and the foundry ventilation air. So far, the highest heat extraction and BTES efficiency (19%) took place in the storage system's sixth full year of operation, when roughly 2200 MWh and 400 MWh were injected into and extracted from the storage respectively. One main reason extraction is not higher is that the quantities and/or the quality of the excess heat for storage are lower than estimated, thus hindering the storage from reaching the necessary temperatures for heat extraction.

New "Smart" Systems for Atmospheric Aerosol and Reactive Gas Sampling in Ambient Air.

Nowadays a recognized need for accurate observations of atmospheric aerosols (AEs) and reactive gases (RGs) exists in the framework of regional, national and global near-surface networks based on permanent or mobile measurement stations. In this context, a paramount and not-trivial issue is related to the correct execution of continuous sampling of ambient air and its subsequent distribution to measurement analyzers hosted inside the stations. Sampling artifacts must be minimized for obtaining reliable pictures of ambient air composition. To respond to this need, a suite of novel “smart” and relatively low-cost systems for the continuous sampling of ambient air was developed in the framework of the 2012–2015 I-AMICA Project. These systems were designed to execute AE and RG measurements according with WMO/GAW and ACTRIS recommendations and standard operation procedures. A particular attention was dedicated to the stabilization and control of the sampling flow rates and temperatures. The analysis of one full year of operations at the WMO/GAW regional station of Capo Granitola (GAW ID: CGR, Italy), allowed to conclude that these systems are effective in meeting the technical requirements for correct execution of AE and RG measurements.

Combined Economic and Experimental Evaluation of Energy Storage for Grid Applications

Batteries will undoubtedly play critical roles in modernizing energy grids, allowing greater penetration of renewable generation and providing services that help grids function. Applying storage technology to grid applications is a business decision that requires potential revenues to be accurately measured to determine economic viability. Using models of storage connected to the California energy grid, we simulate grid-scale applications to estimate such revenues under current market conditions. All calculations are undertaken over two full years of operation of the storage device where a simulation of the grid-connected battery is undertaken so that control and decision are made in real time. Control and decision are made with data available at the time and mimics actual use as it might have happened. The use of a long period of data provides precise estimates as to the values of different applications of the battery. Each simulation results in duty cycles (power profiles) on which the cell-level batteries are tested. We examine the effects of these differing duty cycles on the efficiencies of batteries with various chemsitries. For the first time, we reveal critical tradeoffs between the battery chemistries and the applicability of their energy content, and show that accurate revenue measurement can only be achieved if realistic battery operation in each application is taken into account. The findings in this work could call for a paradigm shift on how the true economic values of energy storage devices could be assessed.

Editorial Note: Welcome to Volume 21 and the year 2018

African Journal of Nephrology (AJN) has completed a full year of operation as a web-based journal. After addressing a few teething problems, the journal is now running smoothly. I wish to thank reviewers, readers and the members of the editorial board for having participated in this endeavour. On behalf of the editorial board, I wish to thank all colleagues who have chosen to submit their valuable work to our journal. A special welcome and thanks to contributors who have submitted their manuscript in French, with an English abstract. They ensure that AJN remains a representative vehicle for nephrology research output in Africa. Volume 20, for the year 2017, has now given way to Volume 21, which will include publications throughout the year 2018. As a tribute, I wish to summarize few highlights of Volume 20. The story of the African Association of Nephrology (AFRAN) by Prof Rashad Barsoum, the founding president of AFRAN, is a very good record of the development of nephrology in Africa. The review of renal physiology in patients with potassium disorders by Prof Mitch Halperin and the review of focal and segmental glomerulosclerosis by Prof John Feehally are excellent updates of the two topics. Original articles and case reports from contributors from various African regions are testament to the active production of nephrology knowledge in Africa. Finally, congress proceedings of the AFRAN Congress in March 2017 in Yaounde (Cameroon) and of the Southern African Transplantation Society Congress in September 2017 in Durban (South Africa) are excellent records of high quality nephrology meetings in Africa. As we are continuing to digitize and preserve our past, I wish to invite everyone to read our archive of publications. I urge everyone who may have copies of old AJN issues or manuscripts that are missing in the archive, to forward them to us to ensure that we make all our past papers available online. In the beginning, AJN started as a newsletter, published by the late Prof Salma Suleiman of Sudan. To complete the AJN archive, we hope to include the past newsletters as a tribute to the late Prof Suleiman. We urge anyone having any copies of the newsletter to forward it to AJN. As in Volume 20 in 2017, Volume 21 will consist of a single issue and include all publications for 2018. They will be added throughout the year as they are accepted for publication. We should expect exciting reviews by experts as in our previous volumes as well as special articles. For our legacy project that was started by Prof Rashad Barsoum, first AFRAN President, we will request the subsequent AFRAN presidents to each submit a review of the period of their tenure. As in the past, we expect to publish original articles as well as interesting case reports, and we encourage regional and national societies to submit the abstracts from their conference proceedings for publication. Finally, I wish to take this opportunity to express my best wishes for the year 2018 to all contributors, reviewers and readers. Alain G Assounga Editor-in-Chief

Gravitational wave spectroscopy of binary neutron star merger remnants with mode stacking

A binary neutron star (BNS) merger event has recently been observed in gravitational waves (GWs). As in the case of binary black holes, GWs generated by BNS consist of inspiral, merger, and post-merger components. Detecting the latter is important because it encodes information about the nuclear equation of state (EOS) in a regime that cannot be probed prior to merger. The post-merger signal, however, can be observed by current detectors only out to~ 10 Mpc. We carry out Monte-Carlo simulations showing that the dominant post-merger signal (the 22 mode) from individual events will likely not be observable even with the Einstein Telescope and Cosmic Explorer (CE), assuming a full year of operation, the latest merger rates, and a detection threshold with signal-to-noise ratio of 5. For this reason, we propose two methods that stack the post-merger signal from multiple events to boost the detection probability. The first method follows a commonly-used practice of multiplying the Bayes factors of individual events. The second method relies on an assumption that the mode phase can be determined from the inspiral waveform, so that coherent mode stacking of the data from different events becomes possible. Both methods significantly improve the chances of detecting the dominant post-merger signal, making a detection very likely after a year of observation with CE for certain EOS. We also show that in terms of detection, coherent stacking is more efficient in accumulating confidence. Moreover, assuming a 22 mode is detected with CE via stacking, we estimate through a Fisher analysis that the peak frequency can be measured to a statistical error of ~ 4-20 Hz for certain equations of state. Such an error corresponds to a NS radius measurement of ~ 15-56 m, a fractional relative error ~ 4 %, suggesting that systematic errors from theoretical modeling (~ 100 m) may dominate the error budget.