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The current status of high temperature electrochemistry-based CO 2 transport membranes and reactors for direct CO 2 capture and conversion
The concept of direct CO 2 capture and conversion has attracted significant interest from industries and academia in recent decades due to its potential to address the current grand challenge of global warming/climate change, rapid depletion of fossil fuels and realization of a future carbon neutral ecosystem. The incumbent benchmark technology for CO 2 capture is the post-combustion flue-gas “amine washing”, which is energy intensive and costly for large-scale commercial implementation. The CO 2 conversion technologies, on the other hand, are still at their infancy with many technical challenges to overcome, but primarily being explored in laboratory-scale, low-temperature, solution-based and high-temperature, solid-oxide-based electrochemical cells with renewable electricity perceived as the energy input. In this article, we provide a comprehensive overview on an emergent class of high-temperature electrochemical CO 2 transport membranes that can capture and convert CO 2 into valuable chemicals in single catalytic reactor fashion. The review starts with the chemistry and transport theory of three basic types of membranes purposely designed for different CO 2 feedstocks and downstream conversions. A range of key functional materials used in these membranes and their microstructural/electrochemical properties important to the CO 2 transport are then thoroughly discussed in conjunction with the effects of surface modifications and operating conditions. Several types of combined CO 2 capture and conversion catalytic reactors based on these membranes are also assessed with a focus on their working principles, system configurations and performance demonstrations. Finally, challenges and prospective of these electrochemical CO 2 transport membranes and their associated conversion reactors are candidly discussed for future development.
Are all identically conserved geometric tensors metric variations of actions? A status report
Not Available
A status review on the thermal stratification modeling methods for Sodium-cooled Fast Reactors
The thermal stratification phenomenon plays a crucial role in the safety of various nuclear systems, including the Gen-III + Light Water Reactors (LWR) and the Gen-IV reactors. The phenomenon is of particular importance for the pool-type Sodium-cooled Fast Reactors (SFRs) because it may cause neutronic and thermal-hydraulic in- stabilities in the reactor core, or lead to damages of both the reactor vessel and in-vessel components due to the growth of thermal fatigue cracking. More significantly, thermal stratification could impede the establishment of the natural circulation during accidental scenarios and introduce uncertainties to the core safety of SFRs. Efforts for modeling of the thermal stratification in SFRs have been made for decades to prevent or mitigate the damage caused by the phenomenon. This paper gives a review of the advances that have been made in recent 10 years on the computational modeling methods for thermal stratification phenomenon in SFRs. These methods can be generally drawn into two categories. The first one is the system-level methods which provide fast-running but approximate calculations, and the second one is the CFD methods which provide high-resolution calculations at high computational expense. Finally, after introducing the efforts that have been made to improve the one- dimensional (1-D) models, the paper envisioned the possible research directions that could be pursued to enhance the modeling of thermal stratification in the near future.
History and status of spent fuel treatment at the INL Fuel Conditioning Facility
Experimental Breeder Reactor II (EBR-II) had an illustrious operational history from 1964 to 1994 as one of the first sodium-cooled fast reactors to use sodium-bonded metallic driver fuels and blankets. EBR-II was a testbed for fuel development and reactor design principles. Following shutdown, it was decided to use electrometallurgical methods to treat the spent fuel and blanket materials for final disposition. Here, this paper provides a brief history of U.S. liquid metal cooled reactor development with emphasis on EBR-II, and a technical description of the electrometallurgical methods.
NuSTEC 1 1Neutrino Scattering Theory Experiment Collaboration http://nustec.fnal.gov. White Paper: Status and challenges of neutrino–nucleus scattering
The precise measurement of neutrino properties is among the highest priorities in fundamental particle physics, involving many experiments worldwide. Since the experiments rely on the interactions of neutrinos with bound nucleons inside atomic nuclei, the planned advances in the scope and precision of these experiments require a commensurate effort in the understanding and modeling of the hadronic and nuclear physics of these interactions, which is incorporated as a nuclear model in neutrino event generators. Lastly, this model is essential to every phase of experimental analyses and its theoretical uncertainties play an important role in interpreting every result.
Status and perspectives of neutrino physics
This review demonstrates the unique role of the neutrino by discussing in detail the physics of and with neutrinos. We deal with neutrino sources, neutrino oscillations, absolute masses, interactions, the possible existence of sterile neutrinos, and theoretical implications. In addition, synergies of neutrino physics with other research fields are found, and requirements to continue successful neutrino physics in the future, in terms of technological developments and adequate infrastructures, are stressed.
Review and status of tool tip frequency response function prediction using receptance coupling
This paper provides a chronological review of publications that implement and advance the receptance coupling substructure analysis (RCSA) approach first applied to tool tip receptance (or frequency response function) prediction for milling applications in 2000. The review topics mimic the RCSA approach, where the tool, holder, and spindle-machine receptances are coupled analytically, and include: tool-holder receptance modeling; connection modeling; spindle-machine receptances; and applications. The review paper summarizes contributions from multiple, international authors (198 papers) to these topics. Additionally, it provides a comprehensive resource for those beginning an investigation into RCSA.
Retail Hydrogen Station Reliability Status and Advances
One of the most vital emerging commercial markets for hydrogen is fuel cell-powered mobility including cars, trucks, and buses. These vehicles are refueled via a network of hydrogen fueling stations, with the highest number of U.S. stations being in California. The numbers of both fuel cell electric vehicles (FCEVs) and hydrogen stations have increased in the last two years, with anecdotal information from FCEV drivers indicating that station reliability is hurting the consumer acceptability of FCEV technologies. Therefore, this study benchmarks the current state of hydrogen station reliability in practice and presents on-going research that is investigating the failures that are contribute to hydrogen station reliability issues. This is accomplished with an analysis of operation, safety, and maintenance data from hydrogen stations and fuel cell electric vehicles to benchmark the maintenance and failure of hydrogen stations and their components. This analysis, of over 5,000 station maintenance events, presents the leading maintenance categories and failure rates, and is a prerequisite to the development of data-driven reliability improvement plans. We present a reliability growth analysis and on-going research into the root causes of failure for dispensers, a particularly failure-prone subsystem.
A status review of photovoltaic power conversion equipment reliability, safety, and quality assurance protocols
Data indicate that the inverter is the element of the photovoltaic plant that has the highest number of service calls and the greatest operation and maintenance cost burden. This paper describes the projects and relevant background needed in developing design qualification standards that would serve to establish a minimum level of reliability, along with a review of photovoltaic inverter quality and safety standards, most of which are in their infancy. We compare stresses and levels for accelerated testing of inverters proposed in the standard drafts, and those proposed by manufacturers and purchasers of inverters. We also review bases for the methods, stress types, and stress levels for durability testing of key inverter components. Many of the test protocols appear to need more comprehensive inclusion of stress factors existing in the natural environment such as wind driven rain, dust, and grid disturbances. Further understanding of how temperature, humidity ingress, and voltage bias affect the inverters and their components is also required. We provide data indicating inconsistent quality of the inverters and the durability of components leading to greater cost for the photovoltaic plant operator. Accordingly, the recommendation for data collection within quality standards for obtaining cost of ownership metrics is made. Design validation testing using realistic operation, environmental, and connection conditions, including under end-use field conditions with feedback for continuous improvement is recommended for inclusion within a quality standard.
Current status of biogas upgrading for direct biomethane use: A review
Anaerobic digestion produces biogas, a mixture of CH 4 and CO 2 , where CH 4 is a low cost, environmentally friendly, and renewable energy source. The application of biogas production is increasing rapidly as a means of reducing the pollution impact of organic biomasses. However, biogas contains unwanted elements such as hydrogen sulfide, carbon monoxide, siloxanes, and carbon dioxide. To remove these elements, several biogas upgrading technologies like water scrubbing, amine scrubbing, pressure swing adsorption, and membrane separation have been developed and are being used at various commercial scales. Problems with these methods are high energy consumption, the use of expensive chemicals, and high operating cost. Therefore, a major effort is currently underway to improve the design of existing methods as well as developing innovative new upgrading technologies such as cryogenic separation and biological upgrading. Here, this review intends to provide a comprehensive overview of the limitations with the existing upgrading technologies along with recent advances in physical, chemical, and biological biogas upgrading technologies (e.g., pressure swing adsorption, membrane separation, biochar adsorption and CO 2 conversion by biological organisms) and further into possible future solutions, such as hybrid systems. Comparative studies of process complexities and associated economic concerns are also provided, and future perspectives that may facilitate research into sustainable biogas upgrading technologies are discussed, focusing in particular on cryogenic separation, novel biological techniques, biochar based upgrading and hybrid technologies incorporating two or more different methods seamlessly integrated.
Regulation of steroid hormones and energy status with cysteamine and its effect on spermatogenesis
Although it is well known that cysteamine is a potent chemical for treating many diseases including cystinosis and it has many adverse effects, the effect of cysteamine on spermatogenesis is as yet unknown. Therefore the objective of this investigation was to explore the effects of cysteamine on spermatogenesis and the underlying mechanisms. Sheep were treated with vehicle control, 10 mg/kg or 20 mg/kg cysteamine for six months. After that, the semen samples were collected to determine the spermatozoa motility by computer-assisted sperm assay method. Blood samples were collected to detect the levels of hormones and the activity of enzymes. Spermatozoa and testis samples were collected to study the mechanism of cysteamine's actions. It was found that the effects of cysteamine on spermatogenesis were dose dependent. A low dose (10 mg/kg) cysteamine treatment increased ovine spermatozoa motility; however, a higher dose (20 mg/kg) decreased both spermatozoa concentration and motility. This decrease might be due to a reduction in steroid hormone production by the testis, a reduction in energy in the testis and spermatozoa, a disruption in the blood-testis barrier, or a breakdown in the vital signaling pathways involved in spermatogenesis. The inhibitory effects of cysteamine on sheep spermatogenesis may be used to model its effects on young male patients with cystinosis or other diseases that are treated with this drug. Further studies on spermatogenesis that focus on patients treated with cysteamine during the peripubertal stage are warranted. - Highlights: • Dose dependent effects of cysteamine on spermatogenesis • A low dose (10 mg/kg) increased spermatozoa motility. • A higher dose (20 mg/kg) decreased both concentration and motility of spermatozoa. • Disruption in the blood-testis barrier caused reduction in concentration and motility.
Challenges in the post-licensing stage of U.S. hydropower development: Current status and some potential solutions
The issuance of a Federal Energy Regulatory Commission (FERC) license is an important milestone in the development process of new U.S. hydropower projects. The complexity and uncertain timeline of the licensing process have been often cited as a key deterrent to new hydropower installations in the United States. However, very little attention has been paid to post-licensing timelines and attrition rates. This article explores the challenges faced by developers in bringing their FERC-licensed hydropower projects to the construction stage. Post-licensing activities to be completed before starting construction include obtaining additional permitting from other federal or state agencies, completing the technical design, securing financing, and in most cases, negotiating a power purchase agreement. For the set of projects that obtained a FERC license between 2007 and 2018, we assembled a dataset—combining information from FERC dockets and responses from a questionnaire to developers—to calculate attrition rates and development timelines and to examine the reasons for delays and cancellations.
Status and Challenges of Density Functional Theory
Here, we discuss some of the challenges facing density functional theory (DFT) and recent progress in DFT for both ground and excited electronic states. We discuss key aspects of the results we have been able to obtain with the strategy of designing density functionals to have various ingredients and functional forms that are then optimized to accurately predict various types of properties and systems with as much universality as possible. Finally, we make specific recommendations of approximate density functionals that are well suited for particular kinds of applications.