Additive manufacturing for solid oxide cell electrode fabrication

© The Electrochemical Society.Additive manufacturing can potentially offer a highly-defined electrode microstructure, as well as fast and reproducible electrode fabrication. Selective laser sintering is an additive manufacturing technique in which three-dimensional structures are created by bonding subsequent layers of powder using a laser. Although selective laser sintering can be applied to a wide range of materials, including metals and ceramics, the scientific and technical aspects of the manufacturing parameters and their impact on microstructural evolution during the process are not well understood. In the present study, a novel approach for electrode fabrication using selective laser sintering was evaluated by conducting a proof of concept study. A Ni-patterned fuel electrode was laser sintered on an yttria-stabilized zirconia substrate. The optimization process of laser parameters (laser sintering rate and laser power) and the electrochemical results of a full cell with a laser sintered electrode are presented. The challenges and prospects of using selective laser sintering for solid oxide cell fabrication are discussed

Biomass combustion systems. A guide for monitoring and efficient operation

In developing countries, biomass represents the main source of energy with 300 to 375 million tonnes being used in small- to medium-scale industries. This industrial use causes local wood supply and associated deforestation problems which can be alleviated by efficient use of the fuel. This publication, which forms part of a series, is intended for use by plant operators and researchers in the field of biomass combustion to enable the evaluation of plant performance and provide the means to improve it. Combustion calculations including stoichiometric air requirements, theoretical flue gas composition and diabatic flame temperatures are explained in detail. Fuel properties of over 140 biomass materials are tabulated. A wide range of equipment is available for biomass combustion, some of which is derived from systems designed for solid fossil fuel combustion. Some of the considerations required to adapt such equipment are covered and a brief review of the different types of solid fuel combustion systems is included. Procedures and instrumentation for measurement of gas composition and temperatures in combustion equipment are reviewed and the advantages and disadvantages of each type of instrument are discussed. Methods for correcting systematic errors in gas temperature measurement are explained. The results of the measurements can be used to calculate the efficiency of the combustion system and the magnitude of the different losses

First steps towards a landslide inventory map of the Central Karakoram National Park

The northeastern part of Pakistan is known to be a region of extremes, where the highest reliefs and the longest glaciers of the world may be found. In this environment, through the multidisciplinary Social, Economic and Environmental Development (SEED) Project the knowledge of the sustainable exploitation possibilities of the Central Karakoram National Park area (CKNP) will be improved. One of this project's objectives is the analysis of the geological hazards giving as output a landslide inventory and a susceptibility map, utilizable as functional tools for a future sustainable territorial planning. The Bagrot Valley, chosen as test site, was partially field surveyed and part of the landslide-prone areas preliminarily identified through DEM analysis, GIS techniques and Analytical Hierarchy Process (AHP) methodology, were later validated on the field. ASTER DEM was used as the basis of morphometric analysis

The importance of phase dynamics in generation of coherent structures

In magnetically confined plasmas (MCP), the transport of heat and particles is determined by collisional and anomalous processes caused by turbulence. A collective effort has been put into modelling the turbulent transport in plasmas using various drift wave (DW) models. However, it is evident that large-scale phenomena have a significant impact on overall transport. Heat transport can be mediated by coherent structures such as streamers and blobs through the formation of avalanche-like events that are intermittent in nature, i.e., localized in time but of large amplitude. Furthermore, at the same time, there are structures such as zonal flows (ZF) and GAMs that are non-linearly generated and mitigate turbulent transport by shearing turbulent eddies. A common denominator for these large-scale structures is the synchronization of smaller scale modes or events to a coherent structure, where phases align in a localized region of space and time. Interestingly, phase synchronization is prevalent in many other fields, such as biological clocks, physiological organisms, and chemical reactors. The dynamical evolution of amplitude and phases have been investigated through simplified equations derived from the Hasegawa - Wakatani (HW) system, where effects of synchronization are studied.Theoretical studies often deal with the amplitudes of the fluctuating quantities and assume that the phases are randomly distributed according to the random phase approximation (RPA) and thus disregard the dynamics of the phases [1,2]. In this approximation, dynamical amplitudes have a slow variation compared to the rapid change of the phases, which are distributed uniformly over a $2 \pi$ interval [3]. There have been a few general approaches to the randomness in turbulence: the RPA, the diagrammatic method by Wyld and the cumulant expansions, with the aim of systematically characterizing intermittent behavior. Unless a specific case is studied, the diagrammatic method has a drawback since there is no consistent small expansion parameter and no normalization procedure available. Moreover, the intuitive picture of the RPA approach is tempting and is thus widely adopted in turbulence theory. The underlying assumption of randomness in the RPA for the phases of Fourier modes in nonlinearly interacting waves cannot be justified since the phases as well as the amplitudes evolve due to non-linear interactions that act on the same time scales for both. Thus, the phases cannot be randomized faster than the amplitudes, see further discussion in Refs. [4,5]. Understanding the generation of coherent structures and the effects of these structures on transport and turbulence is therefore of crucial importance. In regard to plasma dynamics, simplified models are of interest, assuming an expansion of the state in amplitude and phase, i.e., $\phi \sim \phi_0 \exp(i \theta)$, the basic dynamical equations yield one dynamical equation for the amplitude and one for the phase for each field in the model. In previous papers, models using the passive advected scalar [6] and the Burgers equation [1] where it was found that under certain conditions, the RPA assumption can be invalidated using a phase dependent force and the locking of phases may increase the energy transfer to other modes. The assumption of a fully stochastic phase state of the turbulence is more relevant for high values of scale separation with the energy spectrum following a $k^{−7/2}$ decay rate. The dynamic of the three-body interactions between the phases in the non-linear Burgers’ turbulence shows that the phases lock intermittently. This is due to the k dependence of the coupling strength in the non-linear term which reduces strongly for high-k range due to the dampening effect of the dissipation which does not allow locking of the phases of the small scales. For lower scale dependence the asynchronized and synchronized phases differ significantly, and one could expect the formation of coherent modulations in the latter case. Moreover, the HW have been studied [7] and the work on the predator-prey model of DW – ZF dynamics, it is observed that synchronization may be transferred between the two populations [8].In this work, we investigate the role of phase dynamics for turbulent fluctuations in a set of direct numerical simulation (DNS) of homogeneous Taylor-Green driven turbulence, simple 2D rotating turbulence flow. The model is the forced incompressible magnetohydrodynamic (MHD) equations. It should be noted that in the study of coupled oscillators describing chemical reactors, the Kuramoto model has been established, and it has been shown that synchronization occurs when a certain threshold is exceeded. In this case the system is strongly forced to generate a vortex and where the phase locking between close neighbours can be quantified

CAPTCHA Types and Breaking Techniques: Design Issues, Challenges, and Future Research Directions

The proliferation of the Internet and mobile devices has resulted in malicious bots access to genuine resources and data. Bots may instigate phishing, unauthorized access, denial-of-service, and spoofing attacks to mention a few. Authentication and testing mechanisms to verify the end-users and prohibit malicious programs from infiltrating the services and data are strong defense systems against malicious bots. Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is an authentication process to confirm that the user is a human hence, access is granted. This paper provides an in-depth survey on CAPTCHAs and focuses on two main things: (1) a detailed discussion on various CAPTCHA types along with their advantages, disadvantages, and design recommendations, and (2) an in-depth analysis of different CAPTCHA breaking techniques. The survey is based on over two hundred studies on the subject matter conducted since 2003 to date. The analysis reinforces the need to design more attack-resistant CAPTCHAs while keeping their usability intact. The paper also highlights the design challenges and open issues related to CAPTCHAs. Furthermore, it also provides useful recommendations for breaking CAPTCHAs

The impact of intrinsic and extrinsic religiosity on ethical decision-making in management in a non-Western and highly religious country

The primary purpose of this study was to explore the indirect effect of intrinsic religiosity and extrinsic religiosity on ethical intention through ethical judgment. A review of the literature shows the need for more research at the intersection of religiosity and ethics, especially in non-Western, highly religious contexts. This research, therefore, addresses the research question: Do intrinsic religiosity and extrinsic religiosity indirectly impact ethical intention through influencing the ethical judgment of management professionals? Data were gathered from members of the Management Association of Pakistan through a questionnaire. Pearson correlation results show the overall trend between the constructs of interest. Multiple regression results show that both intrinsic religiosity and extrinsic religiosity are significant positive predictors of ethical judgment. Ethical judgment was also found to be a significant, positive predictor of ethical intention. The main contribution of the study is evidence that ethical judgment acts as a mediator between religiosity (whether intrinsic or extrinsic) and ethical intention in a non-Western highly religious context. This research also found that intrinsic religiosity impacts ethical intention directly as well as indirectly through ethical judgment, but extrinsic religiosity influences ethical intention only through its effect on ethical judgment. We discuss our results along with practical and research implications, and limitations of this research are highlighted to guide future research

The impact of intrinsic and extrinsic religiosity on ethical decision-making in management in a non-Western and highly religious country

The primary purpose of this study was to explore the indirect effect of intrinsic religiosity and extrinsic religiosity on ethical intention through ethical judgment. A review of the literature shows the need for more research at the intersection of religiosity and ethics, especially in non-Western, highly religious contexts. This research, therefore, addresses the research question: Do intrinsic religiosity and extrinsic religiosity indirectly impact ethical intention through influencing the ethical judgment of management professionals? Data were gathered from members of the Management Association of Pakistan through a questionnaire. Pearson correlation results show the overall trend between the constructs of interest. Multiple regression results show that both intrinsic religiosity and extrinsic religiosity are significant positive predictors of ethical judgment. Ethical judgment was also found to be a significant, positive predictor of ethical intention. The main contribution of the study is evidence that ethical judgment acts as a mediator between religiosity (whether intrinsic or extrinsic) and ethical intention in a non-Western highly religious context. This research also found that intrinsic religiosity impacts ethical intention directly as well as indirectly through ethical judgment, but extrinsic religiosity influences ethical intention only through its effect on ethical judgment. We discuss our results along with practical and research implications, and limitations of this research are highlighted to guide future research

Human Retroviral Host Restriction Factors APOBEC3G and APOBEC3F Localize to mRNA Processing Bodies

APOBEC3G is an antiviral host factor capable of inhibiting the replication of both exogenous and endogenous retroviruses as well as hepatitis B, a DNA virus that replicates through an RNA intermediate. To gain insight into the mechanism whereby APOBEC3G restricts retroviral replication, we investigated the subcellular localization of the protein. Herein, we report that APOBEC3G localizes to mRNA processing (P) bodies, cytoplasmic compartments involved in the degradation and storage of nontranslating mRNAs. Biochemical analysis revealed that APOBEC3G localizes to a ribonucleoprotein complex with other P-body proteins which have established roles in cap-dependent translation (eIF4E and eIF4E-T), translation suppression (RCK/p54), RNA interference–mediated post-transcriptional gene silencing (AGO2), and decapping of mRNA (DCP2). Similar analysis with other APOBEC3 family members revealed a potential link between the localization of APOBEC3G and APOBEC3F to a common ribonucleoprotein complex and P-bodies with potent anti–HIV-1 activity. In addition, we present evidence suggesting that an important role for HIV-1 Vif, which subverts both APOBEC3G and APOBEC3F antiviral function by inducing their degradation, could be to selectively remove these proteins from and/or restrict their localization to P-bodies. Taken together, the results of this study reveal a novel link between innate immunity against retroviruses and P-bodies suggesting that APOBEC3G and APOBEC3F could function in the context of P-bodies to restrict HIV-1 replication