A memory-based high-speed digital delay line with a largeadjustable length

The digital delay line concept is based on a dynamic three-transistor cell memory, with pointer access and offers high operating frequency, large maximum length, and low power dissipation. The adjustable delay requires only a small overhead for control logic. An experimental chip with 60 K transistors, which utilizes this concept, has been built in a 1.5-μm CMOS technology. The adjustable delay ranges from 1 to 4096 clock cycles for a 4-bit-wide data word. Correct operation of the chip has been verified for clock frequencies in the range of 3 kHz to 30 MHz. Therefore the circuit is suitable for audio as well as video applications     

The effects of e‐beam crosslinking of LDPE on the permeation of hydrocarbons

Polyethylene is a useful material in numerous applications, such as packaging, fuel tanks as well as oil and gas pipes. However, it must be considered that polyethylene is permeable to gases and liquids. Small molecules, such as hydrocarbons, may permeate through the material and cause environmental problems. Consequently, a particular aspect of polymer materials is the requirement of a high permeation resistance against low‐molecular‐weight hydrocarbons. Modifications of the commonly used polyethylene material are necessary to achieve adjusted permeation properties. In this contribution, the effect of electron‐beam crosslinking of polyethylene on the resulting permeation characteristics was investigated. Polyethylene sheets were processed and crosslinked by irradiation with high energy electrons. The formation of a network structure was characterized by gel content determination and by rheological measurements. The permeation properties of the polymer sheets were assessed by a gravimetric method. It is demonstrated that—as a result of the crosslinking process—the permeation of low molecular weight hydrocarbon through polyethylene is reduced with respect to the chain length of the aliphatic substances. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44968.     

Non-quasi-static approach with surface-potential-based MOSFET model HiSIM for RF circuit simulations

We develop a non-quasi-static MOSFET compact model suitable for simulating RF circuits operating under GHz frequency. The model takes into account the carrier dynamics by incorporating the time delay for the carriers to form a channel. Both the time-domain and frequency-domain expressions are successfully derived from the same basic equation by using the proposed modeling methodology, and the consistency of the both representations are verified. The model accuracy in predicting transient currents is demonstrated by comparing with simulation results of a 2D device simulator. The developed NQS model is implemented into SPICE3f5 and achieves stable circuit simulations with only 3%$3\%$ simulation time increase.     

An associative memory-based learning model with an efficient hardware implementation in FPGA

In this paper we propose a learning model based on a short- and long-term memory and a ranking mechanism which manages the transition of reference vectors between the two memories. Furthermore, an optimization algorithm is used to adjust the reference vectors components as well as their distribution, continuously. Comparing to other learning models like neural networks, the main advantage of the proposed model is that a pre-training phase is unnecessary and it has a hardware-friendly structure which makes it implementable by an efficient LSI architecture without requiring a large amount of resources. A prototype system is implemented on an FPGA platform and tested with real data of handwritten and printed English characters delivering satisfactory classification results.     

Permeation of hydrocarbons through organosilane crosslinked LDPE

The importance of polymeric transportation systems has been steadily increasing over the years. It is a useful material in numerous applications, such as packaging, oil and gas pipes, and household items. One particular aspect of polyethylene (PE) is the permeability of small molecules, such as low‐molecular‐weight hydrocarbons. In the present study, PE sheets were crosslinked by grafting and subsequent hydrolysis of organosilanes during a reactive extrusion process. The formation of a network structure was characterized by sol/gel analysis and by rheological measurements. It is shown that as a result of crosslinking the permeation of linear alkanes through the PE is reduced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45374.     

On the validity of conventional MOSFET nonlinearity characterization at RF switching

We analyze the linearity of metal oxide semiconductor field effect transistors (MOSFETs) at radio frequency switching using the conventional extraction method of IP3, measured harmonic distortion (HD), and a surface-potential-based MOSFET model for circuit-simulation. The applicability of the conventional extraction method of IP3 at low frequency to represent IP3 at high frequency is also investigated. At low frequency, measured HD characteristics and extracted IP3 values correspond to the prediction by the model which adopts the quasistatic approximation, i.e., instantaneous carrier response is assumed. Beyond half of the cutoff frequency, the carrier response delay enhances the MOSFET nonlinearity, which is manifested by a decreased first order harmonic and a pronounced curvature of the third order harmonic. Consequently, the conventional extraction method of IP3 value from the intersection point of linearly extrapolated first and third harmonics becomes unreliable.     

A degradation mechanism of EEPROM cell operational margins whichremains undetected by conventional quality assurance

We report an electron-discharge mechanism from the floating gate of charged EEPROM cells during the first charging operation after baking (250°C, 24 h). For an ensemble of measured EEPROM tells the discharge occurs statistically with threshold-voltage reductions up to over 1 V. Responsible is Fowler-Nordheim (FN) tunneling through the interpolyoxide at the edge where the control gate wraps over the floating gate. This FN tunneling is normally suppressed by a localized highly stable electrical passivation, which is automatically generated by programming operations. Baking partly destroys this passivation so that subsequent cell charging removes more electrons from the floating gate by FN tunneling via the interpolyoxide than it adds via the tunneling oxide     

Influence of the degree of exfoliation on the thermal conductivity of polypropylene nanocomposites

The aim of this study was to determine the influence of exfoliated silicate layers on the thermal conductivity of polypropylene nanocomposites. The correlation of thermal conductivity with the degree of exfoliation is examined and compared to common mineral fillers like talcum. The results clearly show that not only the filler content but also the size and number of the main particles (specific surface) influence thermal conductivity significantly. With respect to this, the smaller the particles and the more particles are in the matrix, the higher the increase in thermal conductivity. Compared to common fillers, the increase in thermal conductivity is considerably higher with exfoliated layered silicates and directly depends on the degree of exfoliation. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Tessellation‐Independent Smooth Shadow Boundaries

We propose an efficient and light‐weight solution for rendering smooth shadow boundaries that do not reveal the tessellation of the shadow‐casting geometry. Our algorithm reconstructs the smooth contours of the underlying mesh and then extrudes shadow volumes from the smooth silhouettes to render the shadows. For this purpose we propose an improved silhouette reconstruction using the vertex normals of the underlying smooth mesh. Then our method subdivides the silhouette loops until the contours are sufficiently smooth and project to smooth shadow boundaries. This approach decouples the shadow smoothness from the tessellation of the geometry and can be used to maintain equally high shadow quality for multiple LOD levels. It causes only a minimal change to the fill rate, which is the well‐known bottleneck of shadow volumes, and hence has only small overhead.     

CHC+RT: Coherent Hierarchical Culling for Ray Tracing

We propose a new technique for in‐core and out‐of‐core GPU ray tracing using a generalization of hierarchical occlusion culling in the style of the CHC++ method. Our method exploits the rasterization pipeline and hardware occlusion queries in order to create coherent batches of work for localized shader‐based ray tracing kernels. By combining hierarchies in both ray space and object space, the method is able to share intermediate traversal results among multiple rays. We exploit temporal coherence among similar ray sets between frames and also within the given frame. A suitable management of the current visibility state makes it possible to benefit from occlusion culling for less coherent ray types like diffuse reflections. Since large scenes are still a challenge for modern GPU ray tracers, our method is most useful for scenes with medium to high complexity, especially since our method inherently supports ray tracing highly complex scenes that do not fit in GPU memory. For in‐core scenes our method is comparable to CUDA ray tracing and performs up to 5.94 × better than pure shader‐based ray tracing.