Circuit analysis of an ultrafast junction mixing scanning tunnelingmicroscope

A lumped element circuit model for the operation of a junction mixing scanning tunneling microscope (JM-STM) is presented. Fits from this model show excellent agreement with experimental results in the picosecond time regime. The tip sample capacitance employed in the model was calculated to be 33 fF, using the method of images. By varying the capacitance, various tip/sample geometries can be investigated. Testing the response of the model tunnel junction, for faster electrical pulses, suggests how the JM-STM can be pushed into the femtosecond time regime     

Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency

Crystalline silicon (c-Si) is the dominant semiconductor material in use for terrestrial photovoltaic cells and a clear tendency towards thinner, active cell structures and simplified processing schemes is observable within contemporary c-Si photovoltaic research. The potential applications of porous silicon and related benefits are reviewed. Specific attention is given to the different porous silicon formation processes, the use of this porous material as anti-reflection coating in simplified processing schemes and for simple selective emitter processes and its light trapping and surface passivating capabilities, which are required for advantageous use in thin active cell structures. Our analysis of internal quantum efficiency data obtained on both conventional and thin-film c-Si solar cells has been performed with the aim of describing the light diffusing behaviour of porous Si as well as investigating the surface passivating capabilities. An effective entrance angle of 60° is derived, which corresponds to totally diffuse isotropic light, and the importance of a correction for absorption losses in the porous layer is illustrated. Furthermore, photoconductivity decay measurements of freshly etched porous Si on float-zone p-type Si indicate a strong bias-light dependency and a fast degradation of the surface recombination velocity. © 1998 John Wiley & Sons, Ltd.     

Instruction-Level Fault Tolerance Configurability

Due to modern technology trends such as decreasing feature sizes and lower voltage levels, fault tolerance (FT) is becoming increasingly important in computing systems. Several schemes have been proposed to enable a user to configure the FT at the application level, thereby enabling the user to trade stronger FT for performance or vice versa. In this paper, we propose supporting instruction-level rather than application-level configurability of FT, since different parts of some applications (e.g., multimedia) can have different reliability requirements. Weak or no FT will be applied to less critical parts, resulting in time and/or resource gains. These gains can be used to apply stronger FT techniques to the more critical parts; hence increasing the overall reliability. The paper shows how some existing FT techniques can be adapted to support instruction-level FT configurability, how a programmer can specify the desired FT level of the instructions, and how the compiler can manage it automatically. A comparison between the existing FT scheme EDDI (which duplicates all instructions) and the proposed approach is performed both at the kernel and at full application levels. The simulation results show that both the performance and the energy consumption are significantly improved (up to 50% at the kernel and up to 16% at full application level), while the fault coverage depends on the application. For the full application (JPEG encoder), our approach is only applied to one kernel in order to avoid increasing the programming effort significantly.

Dynamic Faults in Random-Access-Memories: Concept, Fault Models and Tests

The ever increasing trend to reduce DPM levels of memories requires tests with very high fault coverage and low cost. This paper describes an important fault class, called dynamic faults, that cannot be ignored anymore. The dynamic fault behavior can take place in the absence of the static fault behavior, for which the conventional memory tests have been constructed. The concept of dynamic fault will be established and validated for both dynamic and static Random-Access-Memories. A systematic way to develop fault models for dynamic faults will be introduced. Further, it will be shown that conventional memory tests do not necessarily detect its dynamic faulty behavior, which has been shown to exist in real designs. The paper therefore also presents new memory tests to target the dynamic fault class.     

A Deep Learning Spatiotemporal Prediction Framework for Mobile Crowdsourced Services

Mobile Networks and Applications - This papers presents a deep learning-based framework to predict crowdsourced service availability spatially and temporally. A novel two-stage prediction model is...     

A robust and secure perceptual hashing system based on a quantization step analysis

Perceptual hashing is conventionally used for content identification and authentication. It has applications in database content search, watermarking and image retrieval. Most countermeasures proposed in the literature generally focus on the feature extraction stage to get robust features to authenticate the image, but few studies address the perceptual hashing security achieved by a cryptographic module. When a cryptographic module is employed [1], additional information must be sent to adjust the quantization step. In the perceptual hashing field, we believe that a perceptual hashing system must be robust, secure and generate a final perceptual hash of fixed length. This kind of system should send only the final perceptual hash to the receiver via a secure channel without sending any additional information that would increase the storage space cost and decrease the security. For all of these reasons, in this paper, we propose a theoretical analysis of full perceptual hashing systems that use a quantization module followed by a crypto-compression module. The proposed theoretical analysis is based on a study of the behavior of the extracted features in response to content-preserving/content-changing manipulations that are modeled by Gaussian noise. We then introduce a proposed perceptual hashing scheme based on this theoretical analysis. Finally, several experiments are conducted to validate our approach, by applying Gaussian noise, JPEG compression and low-pass filtering.     

Nutritive value of meat-soy mixture

The protein value of meat soy blend was evaluated by utilizing the net protein ratio (NPR), the relative protein value (RPV) and the serum urea content methods. It was compared with that of meat. Casein was used as a reference protein. NPR values indicated that utilization of meat and meat soy proteins are comparable. The study of amino acid pattern shows that sulphur containing amino acids are limiting to almost the same degree in meat and meat soy blend. However, the RPV of meat soy bean blend is slightly higher than that of meat. The lowest serum urea content was that of rats fed meat soy blend. Therefore, the mixing of meat with soy bean did not reduce the nutritive value of meat, on the contrary there is tendency towards improvement.     

Saturation swelling and the seeded emulsion polymerisation of styrene at high ionic strength

The effects of adding inorganic electrolyte (below the critical coagulation concentration) have been investigated in two systems for the emulsion polymerisation of styrene. In one system, potassium chloride, at different concentrations, was added at the end of interval I, using three different ionic emulsifiers: potassium octadecanoate which has a low critical micelle concentration (CMC), potassium dodecanoate and sodium dodecyl sulphate (SDS), which have moderately high CMC. A significant increase in the rate of polymerisation was observed in all cases even at the higher levels of electrolyte at which the rate is reduced if the electrolyte is added from the onset of polymerisation. In the second system, the effects of adding sodium chloride, in concentrations up to 0.2_M, on the seeded emulsion polymerisation of styrene have been followed. A significant increase in the rate was observed as electrolyte level was increased, with no significant change in particle size. Saturation swelling measurements indicated a slight increase in monomer concentration inside the particles as electrolyte concentration was increased. Evaluation of the average number of free radicals per particle, n¯, by a steady state approach indicates an increase in the value of n¯ as electrolyte level is increased. The value of n¯ is below 0.5 but approaches this value at the highest electrolyte concentration. The increased surface area of the particles may account for this effect by increasing the capture efficiency of the radicals by the particles.     

Effect of the drying process on the nutritive value of milk. Part 1. Biochemical composition

Five different brands of instant dry whole milk that are most commonly used, and freeze dried milk were analyzed for nitrogen, fat, ash and 4 inorganic constituents and compared with human milk. The composition of the milks differed considerably. The protein content varied widely, ranging from 11.6 to 24.5%. Fat content did not differ widely, ranging from 24.9 to 29.5%. Freeze dried milk had the highest fat content (42.6%). Three out of the five brands of dry milk studied were spray dried and the remaining two were roller dried. All milks tested contained considerably more sodium, potassium, calcium and phosphorus solid than human milk, some of them the four fold amount of calcium and phosphorus.     

Physico-Chemical Characterizations of Poly(vinylidene fluoride)/Cu3(BTC)2 Composite Membranes Prepared by In Situ Crystal Growth

In this work, we present a simple and fast method for elaborating hybrid membranes by growing metal–organic framework crystals inside a polymer solution. The solution thus obtained was casted then annealed at 90°C for 5 h. This method was tested with poly(vinylidene fluoride) (PVDF) as a piezoelectric polymer and the Cu₃(BTC)₂, BTC = 1,3,5-benzene tricarboxylate, as a filler. The characterization of the obtained membranes by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray diffraction showed the presence of the characteristic signatures of Cu₃(BTC)₂ and the β-phase of PVDF. Moreover, scanning electron microscopy images reveal that the Cu₃(BTC)₂ crystallites have grown along the PVDF membranes. The effect of the filler on both thermal and mechanical properties of the membranes was also studied. POLYM. ENG. SCI., 60:464–473, 2020. © 2019 Society of Plastics Engineers