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As more traditional businesses, such as banking and finance, are transferred to online platforms or the cloud, the deepening of system interaction with users and the improvement of technology-based defence system make cyber attackers focus more on human beings, leading to serious financial consequences. This attack utilising social engineering often exploits human nature's weakness. Its complexity, language variability and inductivity are difficult to defend effectively. Therefore, this paper proposes a model for detecting social engineering attacks based on deep neural network by reviewing current methods for social engineering detection, in terms of phishing, deception and content-based detection, in addition to examining deep learning algorithms with excellent data performance. Through the processing and analysis of natural language in chat history, the attention-based Bi-LSTM is used to capture and mine the context semantics, and the ResNet is used to integrate user characteristics and content characteristics for classification and judgment. By describing the features of social engineering attacks and online conversations, the feasibility and effectiveness of the proposed model are demonstrated from the perspective of algorithm selection and applicability.

Abstract The effect of three-dimensional leakage on the extrapolated endpoint, Z 0 , is studied for non-multiplying, pulsed systems. The three-dimensional nature of the problem is treated accurately by modifying a method developed in an earlier publication on the diffusion length problem. Results are obtained using realistic scattering models for hydrogenous and polycrystalline moderators, and also in the 1-speed approximation, assuming isotropic scattering. The theory is compared with experimental values for particular systems. The variation of Z 0 with B 2 is demonstrated for cubical systems: Z 0 is found to decrease with increasing B 2 for hydrogenous and polycrystalline materials. This dependence is explained by considering the asymptotic spectra and the energy dependence of the neutron mean free path. Tables of Z 0 are included so that experimenters may deduce B 2 for non-cubic systems. The anisotropy of Z 0 is demonstrated by computing the value for each direction of a rectangular parallelepiped.

Abstract Pyrolysis tar and char yields were measured at atmospheric pressure between 400–800 °C in three reactors with significantly different design characteristics: a fluidized bed; a wire-mesh reactor; and a ‘hot-rod’ fixed bed reactor. Ranges of conditions under which results were generally in good agreement were identified using a common sample of Linby (low rank British bituminous) coal. Differences highlighted important non-ideal characteristics in the behaviour of all three systems. The causes of these non-idealities and their implications for the interpretation of pyrolysis data from the three types of reactors are discussed in detail.

Abstract In this study, a methodology is developed to assess the feasibility of a reverse osmosis (RO) desalination system powered by a stand-alone salinity driven pressure retarded osmosis (PRO) technology. First, the proposed hybrid RO–PRO system is analysed as a thermodynamic cycle and its feasibility is mathematically interpreted using a feasible condition (FC) number, several dimensionless operational variables and a number of constraints to represent the objective of zero brine discharge. Then, a study of the stand-alone feasibility of a hybrid seawater RO–PRO system is carried out. The results show that lower RO water recovery and higher dimensionless flow rate improve the stand-alone feasibility of the system. A subsystem, a look inside the PRO, is developed to study the applied pressure and the required membrane area to achieve the operations with optimum FC numbers. It is found that the optimum applied hydraulic pressure is inversely proportional to the dimensionless flow rate in the feasible range of stand-alone operations and more area of membrane is required by a larger FC number. Finally, a case study of a selected operation is presented based on its energy performance, and two influencing factors, the inefficiency of the components and the salinity concentration of the feed water.

This study aims to systematically evaluate the detrimental effects, namely concentration polarization (CP) and reverse solute permeation (RSP), and search for the optimum performance of a scale-up osmotic power assisted reverse osmosis (RO) desalination plant. The simulation clearly shows the performance reductions of the hybrid RO-PRO plant due to the CP and RSP effects. However, in both the co-current and counter-current PRO configurations, when the overall dimensionless flow rate decreases, these performance reductions become less significant. In addition, the counter-current PRO has high effectiveness because of the low theoretical net specific energy consumption (SEC) of RO-PRO. It is observed that more severe reduction due to the CP and RSP effects at high overall dimensionless flow rate shrinks the advantageous performance. Furthermore, PRO feed solutions with different concentrations are studied to evaluate the overall performance of the hybrid system. The results indicate that the advantageous performance can be achieved in a range of the concentration of the PRO feed. And with the increase on the PRO feed concentration, the osmotic energy generation reduces but the un-extracted energy due to the detrimental effects is also reduced.

Abstract A least squares principle is described which uses a penalty function treatment of boundary and interface conditions. Appropriate choices of the trial functions and vectors emplyoed in a dual representation of an approximate solution established complementary principles for the diffusion equation. A geometrical interpretation of the principles provides weighted residual methods for diffusion theory, thus establishing a unification of least squares, variational and weighted residual methods. The complementary principles are used with either a trial function for the flux or a trial vector for the current to establish for regular meshes a connection between finite element, finite difference and nodal methods, which can be exact if the mesh pitches are chosen appropriately. Whereas the coefficients in the usual nodal equations have to be determined iteratively, those derived via the complementary principles are given explicitly in terms of the data. For the further development of the connection between finite element, finite difference and nodal methods, some hybrid variational methods are described which employ both a trial function and a trial vector.

Dual-fuel compression ignition (CI) engine operation with hydrogen is a promising method of using hydrogen gas in CI engines via high-cetane pilot fuel ignition. However, hydrogen dual-fuel operation with neat pilot fuels typically produce: high NOx emissions; and high combustion chamber pressure rise rates (leading to increased “Diesel knock” tendencies). While water-in-fuel emulsions have been used during normal CI engine operation to cool the charge and slow combustion rates in an effort to reduce NOx emissions, these water-in-fuel emulsions have not been tested as pilot fuels during hydrogen dual-fuel combustion. In this work two water-in-biodiesel emulsions are tested as pilot fuels during hydrogen dual-fuel operation. Hydrogen dual-fuel operation generally produces at best comparable thermal efficiencies compared with normal CI engine operation, while the emulsified biodiesel pilot fuels generally increase thermal efficiencies when compared with the neat biodiesel pilot fuel during dual-fuel operation. There is also a clear reduction in NOx emissions with emulsified pilot fuel use compared with the neat pilot fuel. The thermal efficiency increase is more apparent at higher engine speeds, while the NOx reduction is more apparent at lower speeds. This is due to two conflicting effects (exclusive to emulsified pilot fuel) that occur in tandem. The first is the cooling effect of water vapourisation on the charge, while the second is the microexplosion phenomenon which enhances fuel-air mixing. The NOx emission reduction is due to the emulsified pilot fuel lowering pressure rise rates compared with the neat pilot fuel, while the efficiency increase is due to a more homogeneous charge resulting from the violent microexplosion of the emulsified pilot fuel. Smoke, CO, HC and CO2 emissions remain comparable to neat pilot fuel tests. Overall, emulsified pilot fuels can reduce NOx emissions and increase thermal efficiencies, however not at the same instance and under different operating conditions. The general trends of reduced power output, reduced CO2 and increased water vapour emission during hydrogen dual-fuel operation (with neat pilot fuels) are also maintained.

Abstract In this work the concept of exergy is used to define criteria of performance of thermal plant. Different criteria are defined for plants with useful outputs expressible in terms of exergy and those without. General methods for formulating criteria of performance for specific thermal plants are outlined and a number of examples of application of steadily operating plants of open and closed type are considered. Also, expressions for the irreversibility rates of the plants are given. In an appendix, an expression for the energy balance for the general case of a control region undergoing a non-steady process with chemical reaction is derived.