Low Penalty Research Articles

Corporate Political Connections and Favorable Environmental Regulation

We examine whether the Environmental Protection Agency (EPA) uniformly enforces the Clean Air Act for politically connected and unconnected firms using a close election setting. We find no difference in regulated pollutant emissions or EPA investigations between the two groups, though connected firms experience less regulatory enforcement and lower penalties. These results are more pronounced for firms connected to politicians capable of influencing regulatory bureaucrats and for connected firms that are more important to their supported politicians. Taken together, our results show that campaign contributions can indirectly benefit firms by way of reduced environmental regulatory enforcement and penalties.

Coal-fired chemical looping combustion coupled with a high-efficiency annular carbon stripper

Coal-fired chemical looping combustion (CLC) is a promising technology with inherent CO2 separation with a low energy penalty. One of challenges for coal-fired CLC is that char particles with slow gasification kinetics can be easily transferred into the air reactor (AR) by circulated oxygen carrier (OC), thereby decreasing the carbon capture efficiency. An annular carbon stripper (CS) was proposed to efficiently separate the char particles from the mixture of OC and char. A hot system of 10 kWth CLC unit coupled with an annular CS was designed, built, and operated in order to investigate the separation performance of an annular CS at high temperature (850-950 °C). Vietnamese ilmenite was used as OC to burn Shenfu bituminous coal. The system achieved a stable solid circulation at a high temperature with steady coal feeding, and total operation reached 100 h with a thermal input of 3-5 kWth. A 90%-95% char separation efficiency was achieved by the annular CS in various tests, and the carbon capture efficiency reached 95% at 950 °C. A special particle sampling device was designed to collect solid particles from the dense phase of CLC reactor during the continuous operation stage. It was found that the char mass faction in the FR dense phase was 0.45%-5.5% and a fraction of char adhered to the ilmenite surface, which was difficult to separate by the annular CS. Additionally, the sintering and agglomeration of ilmenite was not observed during continuous operation at 850-950 °C. Furthermore, through extrapolating experimental results, it is predicted that 90% carbon capture efficiency can be achieved by using this new annular CS in a scaled-up CLC system.

Pulsed electrochemical synthesis of formate using Pb electrodes

Lead cathodes show decreasing Faradaic Efficiency (FE) in electrochemical conversion of CO2 to formate, favoring hydrogen, within minutes of operation in KHCO3 electrolyte at −1 to −1.3 V vs RHE. Periodic anodic polarization (pulsed electrochemistry) is demonstrated to result in a high time-averaged FE towards formate. Specifically, an anodic polarization time of 0.1–1 s is sufficient to obtain a Pb-surface providing an averaged formate FE of 30–50%, when the cathodic polarization time is limited to a few seconds. A Pourbaix diagram and Raman spectra are provided, which show that PbCO3 is formed on the surface of the cathode in KHCO3 electrolyte at anodic potential (0.05 V vs RHE), which compound is likely inducing the high FE towards formate. Our method thus provides a means to operate Pb electrodes in electrochemical CO2 reduction with high stability, at a low energy penalty.

Multicycle Study on Chemical Looping Combustion with a CaSO4-CaO Mixed Oxygen Carrier

Abstract Chemical looping combustion (CLC) is a carbon capture technology which enables CO2 capture with low net efficiency penalty. Calcium sulfate (CaSO4) is an optional oxygen carrier for commercial use, but its usage is limited due to sulfur dioxide (SO2) emission. This study approaches this issue by adding CaO species into the CaSO4 oxygen carrier to inhibit the release of SO2 from CaSO4 oxygen carrier. In this study, the cyclical tests of a CaSO4-based oxygen carrier under alternating reducing and oxidizing conditions were performed at 900 °C and 800 °C respectively in a tubular furnace reactor at atmospheric pressure. The effects of reducing gas concentration and molar ratio of CaO/CaSO4 on the performance of CaSO4-CaO oxygen carrier were studied in terms of CO2 yields, Environmental factors of SO2 and COS, molar ratios of gas sulfides to CO2 generated in fuel reactor, and molar ratios of SO2 and COS to total carbon inlet. The use of CaO additive increased the yields of CO2 obviously. The release of COS in the fuel reactor and SO2 in the air reactor decreased, but while the overall release of SO2 in the fuel reactor increased. However, for per mole CO2 generation, less gas sulfides released from the fuel reactor. High concentrations of CO were beneficial for CO2 production and a low SO2 environmental factor, and meanwhile, the molar ratios of SO2 released to inlet CO {{\text{n}}_{{\text{S}}{{\text{O}}_2}}}/{{\text{n}}_{{\text{CO}}}} decreased. However, it led to a drop in CO2 yield and an increase in COS environmental factor. As a whole, the use of CaO additive and higher CO concentration both accelerated the parallel CaSO4 reductions in fuel reactor, especially the selectivity of CaSO4 reduction to CaS.

Multisources of Energy Contracting Strategy with
 an Ecofriendly Factor and Demand Uncertainties

This study presents a mathematical formulation to optimize contracting capacity strategiesof multisources of energy for institutional or industrial consumers considering demand uncertainties.The objective consists of minimizing the total costs composed of the different types of energy contractcapacity costs, penalty price, and an ecofriendly factor. The penalty price is charged on the demand ofenergy exceeding the total contract capacities. The ecofriendly factor encourages the use of renewableenergy and reduces the traditional energy used in the optimal mix of energy sources. The proposedmodel is tested based on demand of energy inspired from real data. These numerical experiments areanalyzed to illustrate the impact of encouraging the use of renewable energy sources by introducingthe ecofriendly factor and the influence of penalty price and uncertainty in the demand of energy.The results show that in the presence of low penalty price or low uncertainty a large amount ofecofriendly support is needed for using more renewable energy sources in the optimal contractcapacity combination.

A Foreground Self-calibration Technique for High-Resolution Switched-Current R-2R Digital-to-Analog Converters

A foreground calibration technique for switched-current R-2R digital-to-analog converter is proposed. To implement the method, some intermediate nodes are added to the circuit and calibration is done using these nodes to circumvent both current source and resistor mismatches at the output node. A 12-bit, 500-MHz DAC is designed in 0.18 $$\upmu $$m standard CMOS technology with the proposed technique. Simulation results verify that the degraded DAC performance due to the mismatch effects enhances up to 11.5 bits after calibration, imposing a very low power penalty.

Impact of Rigidity on Molecular Self-Assembly.

Rigid, cage-like molecules, like diamondoids, show unique self-assembly behavior, such as templating 1-D nanomaterial assembly via pathways that are typically blocked for such bulky substituents. We investigate molecular forces between diamondoids to explore why molecules with high structural rigidity exhibit these novel assembly pathways. The rigid nature of diamondoids significantly lowers configurational entropy, and we hypothesize that this influences molecular interaction forces. To test this concept, we calculated the distance-dependent impact of entropy on assembly using molecular dynamics simulations. To isolate pairwise entropic and enthalpic contributions to assembly, we considered pairs of molecules in a thermal bath, fixed at set intermolecular separations but otherwise allowed to freely move. By comparing diamondoids to linear alkanes, we draw out the impact of rigidity on the entropy and enthalpy of pairwise interactions. We find that linear alkanes actually exhibit stronger van der Waals interactions than diamondoids at contact, because the bulky structure of diamondoids induces larger net atomic separations. Yet, we also find that diamondoids pay lower entropic penalties when assembling into contact pairs. Thus, the cage-like shape of diamondoids introduces an enthalpic penalty at contact, but the penalty is counterbalanced by entropic effects. Investigating the distance dependence of entropic forces provides a mechanism to explore how rigidity influences molecular assembly. Our results show that low entropic penalties paid by diamondoids can explain the effectiveness of diamondoids in templating nanomaterial assembly. Hence, tuning molecular rigidity can be an effective strategy for controlling the assembly of functional materials, such as biomimetic surfaces and nanoscale materials.

A Compact Integrated Receiver Optical Sub-Assembly With High Sensitivity and Low Crosstalk for 100 Gb/s Ethernet Systems

A 25Gb/s guardring-free planar AlInAs avalanche photodiode (APD) and 100-Gb/s APD receiver optical sub-assembly (ROSA) employing a quasi-collimated beam for reducing the optical loss and optical demultiplexer (DEMUX) size are demonstrated for a 40-km optical link. The APD so fabricated achieves a very low dark current of 63 nA at a multiplication factor of 10, with a high gain-bandwidth product of 225 GHz due to the optimum multiplication layer and absorption layer. Additionally, the assembled APD ROSA exhibits a high receiver sensitivity of more than −23 dBm optical modulation amplitude (OMA) (BER = 5.0 × 10−5) at temperatures ranging from −5 to 80 °C for each lane. Investigating the transmission over fibers with dispersions of −119 and +40 ps/nm reveals that a sufficiently low penalty of less than 0.9 dB is obtained for all lanes. Furthermore, it is confirmed that the APD ROSA suffers little crosstalk penalty thanks to the isolation achieved by this design of optical DEMUX.

Mechanism of discrimination of isoleucyl-tRNA synthetase against nonproteinogenic α-aminobutyrate and its fluorinated analogues.

Isoleucyl-tRNA synthetase (IleRS) is a paradigm for understanding how specificity against smaller hydrophobic substrates evolved in both the synthetic and editing reactions. IleRS misactivates nonproteinogenic norvaline (Nva) and proteinogenic valine (Val), with a 200-fold lower efficiency than the cognate isoleucine (Ile). Translational errors are, however, prevented by IleRS hydrolytic editing. Nva and Val are both smaller than Ile by a single methylene group. How does the removal of one additional methylene group affects IleRS specificity? We found that the nonproteinogenic α-aminobutyrate (Abu) is activated 30-fold less efficiently than Nva and Val, indicating that the removal of the second methylene group comes with a lower penalty. As with Nva and Val, discrimination against Abu predominantly originated from a higher KM . To examine whether increased hydrophobicity could compensate for the loss of van der Waals interactions, we tested fluorinated Abu analogues. We found that fluorination further hampered activation by IleRS, and even more so by the evolutionary-related ValRS. This suggests that hydrophobicity is not a main driving force of substrate binding in these enzymes. Finally, a discrimination factor of 7100 suggests that IleRS is not expected to edit Abu. However, we found that the IleRS editing domain hydrolyzes Abu-tRNAIle with a rate of 40s-1 and the introduction of fluorine did not slow down the hydrolysis. This raises interesting questions regarding the mechanism of specificity of the editing domain and its evolution. Understanding what shapes IleRS specificity is also of importance for reengineering translation to accommodate artificial substrates including fluorinated amino acids. ENZYMES: Isoleucyl-tRNA synthetase (EC 6.1.1.5), leucyl-tRNA synthetase (EC 6.1.1.4), valyl-tRNA synthetase (EC 6.1.1.9).

A single event upset hardened flip-flop design utilizing layout technique

A novel Quatro-based flip-flop design with low penalty was proposed. By utilizing layout technique, SEU hardness was achieved in this design because of charge sharing between the introduced PMOS transistors. Both the proposed design and the reference flip-flop were fabricated in a 65 nm standard CMOS technology. The pulsed laser experiment results demonstrate that the new design has a larger upset threshold and lower SEU error rate compared with the reference. The area and delay penalties are not significant, i.e., 13% and 37%, respectively.

Large eddy simulation of tubular reactors with spherical dimples

Spherical dimples are implemented in heat exchanger channels to enhance heat transfer at a low pressure drop penalty. This combination of enhanced heat transfer and low pressure drop is also valuable for reactive applications such as steam cracking as this allows to increase product selectivity and reduce fouling. Large eddy simulations (LES) show the presence of asymmetric vortex structures inside the spherical dimples if they are implemented in a tubular reactor for steam cracking. Of all investigated geometric parameters, dimple depth and phase difference between consecutive rows is seen to have the greatest impact on the flow behavior. Spherical dimples in a tube enhance heat transfer up to 43% and increase pressure drop by only 54% relative to a bare tube. Relative to a ribbed tube, spherical dimples in tubes can reduce the pressure drop by half without impacting the heat transfer capabilities of the tube. The impact of these enhancements on product yields and run length is assessed via reactive simulations, benchmarking dimpled reactors against a non-enhanced reactor and industrially applied ribbed reactors. These simulations show the superior performance of dimpled reactors: the reduced fouling allows to increase the run length by up to 40% without a significant impact on product selectivities.

Topology optimization of liquid-cooled microchannel heat sinks: An experimental and numerical study

Electronics cooling is always a critical challenge for its small profile and high heat flux. Various microchannel heat sinks have been proposed in literature to achieve reliable and energy efficient cooling effect. They are mainly different patterned fin shapes originated from researchers’ experience. In this paper, we present the process of designing liquid-cooled microchannel heat sink fin geometries based on a numerical method, topology optimization. The optimization model is developed to find designs that satisfy heat transfer requirement with low pressure drop penalty. It is implemented based on a derived accurate 2D model with minimizing pressure drop as objective and average junction temperature as a constraint. Parameter study for different velocities and junction temperature constraints is performed. The optimized structures are then post processed under geometry constraints and analyzed by 3D CFD simulation. Size optimization is implemented on conventional straight channel heat sinks, which serve as the benchmark cases. Moreover, an experimental test loop is built to validate the 3D simulation of topology optimized heat sinks and straight channel heat sinks. The performance comparison shows that the topology optimized heat sinks could save up to 50.9% pumping power under the same thermal performance requirement. Detailed CFD analysis is then engaged to examine their thermohydraulic characteristics and reveal the reasons for their superior performance.

Kinetic enhancement of capturing and storing greenhouse gas and volatile organic compound: Micro-mechanism and micro-structure of hydrate growth

The use of hydrate-based technology for gas capture and storage is highly attractive for environmental mitigation, as it entails low energy penalties and provides gas storage density maximization and long-term storage stability. Although this method has been investigated in extensive researches, its development is restricted by the obscure underlying gas capture micro-mechanisms, elusive micro-structures of stored forms, and insufficient hydrate film growth rates. In this study, the Magnetic Resonance Imaging technique was employed to analyze the hydrate growth micro-processes for greenhouse gas (imitated by CO2, CH4, and various fractions of CO2-CH4 mixed gases) and volatile organic compound (simulated by C2H4 and C2H2 gases) capture and storage. The hydrate film growth was enhanced with the addition of 288 ppm sodium dodecyl sulfate (SDS), which significantly improved the hydrate growth in the cases of hydrocarbon gases, but not CO2 gas due to the competing adsorption of bicarbonate and dodecyl sulfate ions. With SDS, hydrocarbon gas hydrates grew via the patchy model at 65–105 mm/s, and 65–95% liquid water was converted into hydrates for gas capture and storage. However, only about 1.4% water was converted into CO2 hydrates with SDS, at 10.4 mm/s. Thus, a multi-pressure control mechanism for secondary hydrate growth was developed to promote CO2 capture and storage, based on a large amount of dissolved CO2 gas compared to the other investigated gases. The enhanced CO2 capture has important implications for the optimized harmful gas sequestration, due to preferentially patchy hydrate morphologies and associated impacts on permeability.

Tariff for reactive energy consumption in household appliances

The use of inefficient household appliances and their poor power quality results in energy wastage in residential buildings. These appliances also force the power system to operate at low power factor which results in an ineffective energy utilization. This paper reports the energy consumption pattern of mostly used household appliances individually and collectively over a year. Their power quality parameters are measured through experimentation to calculate the reactive energy consumed by household appliances. This paper also proposes the reactive energy tariffs to enhance the awareness among domestic consumers to make efficient use of household appliances. Currently the reactive power management is being dealt for only the industrial consumer by imposing low power factor penalty. This research estimated that Lahore Electric Supply Company (LESCO) can generate a revenue of almost 150 million US dollars in one year from household consumers by applying three part tariff scheme on reactive energy. By improving the power factor it is estimated that an energy conservation of 1.1 × 109 kWh per annum is also possible. Thus the proposed tariff for reactive energy encourages the domestic consumers to get involved actively in energy conservation while enabling the energy utilities to transfer more active energy to consumers without the expansion of the distribution network.

Efficient compute node-local replication mechanisms for NVRAM-centric data structures

The long-awaited nonvolatile random-access memory technology NVRAM is finally publicly available on the market and requires significant changes to the architecture of in-memory database systems. Since such hybrid DRAM–NVRAM database systems may be able to keep the primary data solely persistent in the NVRAM, efficient replication mechanisms need to be considered to prevent base data losses and to guarantee high availability in case of various persistent memory failures. In this article, we argue for a software-based replication approach and present compute node-local mechanisms to provide the building blocks—generally available for most platforms—for an efficient NVRAM replication with a low latency and minimal throughput penalty. Within our evaluation, based on both real NVRAM hardware and DRAM-backed emulation, we measured up to 10$$\times $$ less overhead for our optimized replication mechanisms compared to the basic replication mechanism of the Intel persistent memory development kit PMDK. Finally, we present a lightweight switching approach for enabling the adaptive online selection of the best replication mechanism for a given situation.

White-collar crime in academia: Trends in digital academic dishonesty over time and their effect on penalty severity

This study explored patterns of change over time in penalties for conducting academic dishonesty (AD), following a previous study (Friedman Blau & Eshet-Alkalai, 2016) that reported lower penalties for digital AD offenses compared to analog ones across two years. In the present study, we examined whether this trend changes over time, and what could explain it. We offered two contradicting hypotheses: the regulations hypothesis suggests that the gap between penalties for analog and digital AD caused since it takes time for academic institutes to adjust their regulations to digital dishonesties. Therefore, this gap will diminish and eventually disappear. The perception hypothesis suggests that the penalty gap will remain stable, since it reflects the perception of digital AD as a “white-collar” offense. Contrary to previous studies that used self-reported measurements of AD perceptions, this study analyzed Disciplinary Committee's protocols, which contains a more objective descriptions of type of AD, student's explanations, and penalty types. These protocols provide information about the actual behavior of students and faculty, and not about their opinions. We analyzed the entire volume of 628 university's protocols collected during four consecutive years. Findings clearly demonstrated that the trend of lower penalties for digital offenses remained stable across four years. Results support the perception hypothesis, suggest that this phenomenon relates to the perception of digital AD as a “white-collar crime”. Like other white-collar crimes, is perceived as less harmful and therefore, punished less severely than other crimes. This claim is also supported by our findings that motivations to behave unethically, which students reported to the Discipline Committee, influenced penalties' severity in analog, but not in digital settings. Unexpectedly, a consistent gender-gap was found in penalties' severity for both digital and analog offenses, indicating that women were punished more severely than men. This dissimilarity in penalizing AD offenses remained stable over the studied period. We discuss theoretical and practical implications of these findings.

Three-dimensional multiphase full-loop simulation of directional separation of binary particle mixtures in high-flux coal-direct chemical-looping combustion system

Coal-direct chemical-looping combustion (CDCLC) is a promising coal combustion technique that provides CO2 capture with a low energy penalty. In this study, we developed a three-dimensional Eulerian–Eulerian multiphase full-loop model for simulating the circulation and separation of binary particle mixtures in a novel high-flux CDCLC system. This model comprised a high-flux circulating fluidized bed as the fuel reactor (FR), a counter-flow moving bed as the air reactor (AR), a high-flux carbon stripper, two downcomers, and two J-valves. This model predicted the main features of complex gas–solid flow behaviors in the system. The simulation results showed that quasi-stable solid circulation in the whole system could be achieved, and the FR, AR, and J-valves operated in a dense suspension upflow regime, a near-plug-flow regime, and a bubbling fluidization regime, respectively. The multiphase flow model of binary particle mixtures was used to predict the mechanisms of directional separation of binary particle mixtures of an oxygen carrier (OC) and coal throughout the system. A decrease in the baffle aspect ratio of the inertial separator improved the coal selective separation efficiency but resulted in a slight decline in the OC selective separation; this is believed to be the result of weakening of particle collisions with the baffle. A higher FR gas velocity had a slightly negative effect on the OC selective separation efficiency, but improved the coal selective separation efficiency; this can be attributed to an increase in the particle-carrying capacity of the gas stream. A decrease in the coal particle size led to better entrainment of the coal particles by the gas stream and this increased the coal selective separation efficiency. In real CDCLC applications, the operating variables for separation of binary particle mixtures should be comprehensively assessed to determine their positive and negative effects on the carbon capture efficiency, OC regeneration efficiency, gas leakage restraint, energy consumption, and fuel conversion.

Driving simulator-based training to improve self-rating ability of driving performance in older adults \u2013 a pilot study

ObjectiveThe aim was to investigate the potential of using simulator-based training (SBT) to improve older drivers' self-rating ability and to compare two forms of feedback; corrective versus corrective and rewarding feedback.MethodThe study was designed to study the possibility of training for self-rated driving ability in a simulator, and the impact of corrective (errors made) feedback versus corrective (errors made) and rewarding (correct behaviour) feedback during training. In total, 21 older drivers (mean age 78.5, SD=3.9 years) were trained and assessed in the driving simulator. Driving performance was assessed by penalty scores as well as self and expert ratings.ResultsThe average deviation from correctly rated ability (own vs. expert) changed from -0.7 (under-rating) to 0.1 at the final training and assessment occasion; i.e., drivers ratings became more like the expert's rating or, in other terms, better calibrated. The individuals with the largest deviations from the expert's rating initially improved their self-rating ability the most. There were no differences between the two feedback groups in terms of their ability to self-rate, but rewarding feedback had a positive effect on penalty scores. The SBT showed positive training effects on the ability to self-rate one's driving ability, and rewarding feedback contributed to lower penalty scores. However, simulator sickness was a shortcoming that needs to be adressed, and the optimal form of feedback should be further investigated.

Reinforcement Learning for Slicing in a 5G Flexible RAN

Network slicing enables an infrastructure provider (InP) to support heterogeneous 5G services over a common platform (i.e., by creating a customized slice for each service). Once in operation, slices can be dynamically scaled up/down to match the variation of their service requirements. An InP generates revenue by accepting a slice request. If a slice cannot be scaled up when required, an InP has to also pay a penalty (proportional to the level of service degradation). It becomes then crucial for an InP to decide which slice requests should be accepted/rejected in order to increase its net profit. This paper presents a slice admission strategy based on reinforcement learning (RL) in the presence of services with different priorities. The use case considered is a 5G flexible radio access network (RAN), where slices of different mobile service providers are virtualized over the same RAN infrastructure. The proposed policy learns which are the services with the potential to bring high profit (i.e., high revenue with low degradation penalty), and hence should be accepted. The performance of the RL-based admission policy is compared against two deterministic heuristics. Results show that in the considered scenario, the proposed strategy outperforms the benchmark heuristics by at least 23%. Moreover, this paper shows how the policy is able to adapt to different conditions in terms of 1) slice degradation penalty versus slice revenue factors, and 2) proportion of high versus low priority services.

Environmental impacts of a chemical looping combustion power plant

Chemical Looping Combustion (CLC) is a promising CO2 capture option since it inherently separates CO2 from other flue components, theoretically with low energy penalty. Here, a Life Cycle Assessment model was developed of a theoretical hybrid CLC (HCLC) power plant facility utilising experimental data for CuO based oxygen carrier (OC) production and oxygen capacity. Power plant models with and without post-combustion CO2 capture, recognised as the most mature capture technology, acted as environmental performance targets. Results show that when OC is produced at lab-scale without optimisation, almost all (>99.9%) lifecycle impacts per kWh electricity from an HCLC plant derive from the specific OC material used, giving a total of ˜700 kg CO2eq/kWh. This is related to high electrical input required for OC processing, as well as high OC losses during production and from plant waste. Only when processing parameters are optimised and OC recycling from plant waste is implemented - reducing fresh OC needs – is the environmental impact lower than the conventional technologies studied (e.g. 0.2 kg CO2 eq/kWh vs. ˜0.3-1 kg CO2 eq/kWh, respectively). Further research should thus focus on identifying OCs that do not require energy intensive processing and can endure repeated cycles, allowing for recycling.