Adhesion studies of CVD copper metallization

The adhesion of chemical vapor deposition (CVD) Cu thin films to various barriers was observed to improve with a post-deposition anneal or a physical vapor deposition (PVD) Cu flash layer on the barrier before depositing CVD Cu. The ambient exposure of the barrier before the deposition of CVD Cu has been observed to lead to degradation of adhesion in both CVD Cu seed and CVD/PVD Cu high vacuum integrated metallization schemes. The integrated CVD and PVD Cu deposition scheme exhibits better adhesion due to the inherent annealing provided during the PVD deposition which is carried out at temperatures between 300 and 400°C. We have evaluated both qualitative and quantitative tests — tape test, Stud pull test and 4-point bend test — in understanding adhesion and observed that each of these tests give different details of interface breakdown.     

Cost-effective traffic grooming in WDM rings

We provide network designs for optical add-drop wavelength-division-multiplexed (OADM) rings that minimize overall network cost, rather than just the number of wavelengths needed. The network cost includes the cost of the transceivers required at the nodes as well as the number of wavelengths. The transceiver cost includes the cost of terminating equipment as well as higher-layer electronic processing equipment, which in practice can dominate over the cost of the number of wavelengths in the network. The networks support dynamic (i.e., time-varying) traffic streams that are at lower rates (e.g., OC-3, 155 Mb/s) than the lightpath capacities (e.g., OC-48, 2.5 Gb/s). A simple OADM ring is the point-to-point ring, where traffic is transported on WDM links optically, but switched through nodes electronically. Although the network is efficient in using link bandwidth, it has high electronic and opto-electronic processing costs. Two OADM ring networks are given that have similar performance but are less expensive. Two other OADM ring networks are considered that are nonblocking, where one has a wide-sense nonblocking property and the other has a rearrangeably nonblocking property. All the networks are compared using the cost criteria of number of wavelengths and number of transceivers     

Routing and wavelength assignment in all-optical networks

Considers routing connections in a reconfigurable optical network using WDM. Each connection between a pair of nodes in the network is assigned a path through the network and a wavelength on that path, such that connections whose paths share a common link in the network are assigned different wavelengths. The authors derive an upper bound on the carried traffic of connections (or equivalently, a lower bound on the blocking probability) for any routing and wavelength assignment (RWA) algorithm in such a network. The bound scales with the number of wavelengths and is achieved asymptotically (when a large number of wavelengths is available) by a fixed RWA algorithm. The bound can be used as a metric against which the performance of different RWA algorithms can be compared for networks of moderate size. The authors illustrate this by comparing the performance of a simple shortest-path RWA (SP-RWA) algorithm via simulation relative to the bound. They also derive a similar bound for optical networks using dynamic wavelength converters, which are equivalent to circuit-switched telephone networks, and compare the two cases. Finally, they quantify the amount of wavelength reuse achievable in large networks using the SP-RWA via simulation as a function of the number of wavelengths, number of edges, and number of nodes for randomly constructed networks as well as de Bruijn networks. They also quantify the difference in wavelength reuse between two different optical node architectures     

Fault tolerant multiwavelength optical rings with limitedwavelength conversion

This paper presents methods for recovering from channel failures, link failures, and node failures in wavelength-division multiplexed (WDM) point-to-point links and ring networks with limited wavelength conversion/switching capabilities at the nodes. Different recovery schemes are presented to handle each type of failure. Each scheme is evaluated based on the network hardware configuration required to support it and the performance and management overheads associated with fault recovery. Although similar recovery techniques have been used in conventional networks such as SONET, the constraints due to limited wavelength conversion require new and more complex solutions     

A hybrid analysis/simulation for ATM performance with application to quality-of-service of CBR traffic

A discrete time queueing model for the performance of an ATM system is analyzed using matrix analytic methods. Time is segmented into slots with each slot equal to the transmission time of one ATM cell. The ATM system is modeled as a single server queue with Markovian arrivals and service time equal to one slot. The arrival process includes as a special case the superposition of on-off sources, possibly heterogeneous. The queueing model is of the M/G/1 type. By exploiting the structure of the M/G/1 type Markov chain, the complexity of the solution to the problem is reduced to only the inversion of a 2×2 matrix irrespective of the size of the Markov chain. This simplification allows us to investigate Constant Bit Rate (CBR) traffic performance (or quality-of-service) issues through a hybrid analysis/simulation approach. Specifically, we analyze the impact of on-off background traffic on the probability of consecutive cell losses, cell delay variation, and traffic shaper or playback buffer underflow and overflow probabilities of CBR traffic sources.     

FibGeoPresent: A Highly Secured and Geographic Coordinate System Based Authenticated Lightweight Block Cipher for Smart System

Wireless Personal Communications - Multi-user multiple input multiple output (MU-MIMO) serves multiple users simultaneously by sharing the same channel and bandwidth. The performance degrades in...     

Catalytic hydrodenitrogenation of basic and non-basic nitrogen compounds in Athabasca bitumen distillates

The denitrogenation of distillates derived from Athabasca bitumen over several unpromoted and promoted molybdenum oxide/alumina catalysts has been studied. The removals of both the basic and non-basic nitrogen compounds are compared for a heavy gas oil and a coker kerosene distillate. The addition of MoO₃ to alumina had a much more pronounced effect on the removal of non-basic nitrogen compounds than of basic ones. Comparison of several nickel- and cobalt-promoted catalysts showed that the denitrogenation activity of catalysts increased with the promoter/molybdenum ratio up to an atomic ratio of about 0.6. Any further increase in the atomic ratio did not change the denitrogenation activity. As this trend was observed with catalysts made with different supports, as well as with varying MoO₃ concentrations, it is believed to be independent of physical properties such as surface area. Basic nitrogen removal also followed similar trends with increasing promoter/ molybdenum ratio.     

A comprehensive methodology for runout tolerance evaluation using discrete data

Runout is a composite tolerance that is usually specified to ensure proper alignment and rotational accuracy for axially symmetric features. The procedure for evaluation of runout defined in American Society of Mechanical Engineers (ASME) Y14.5M-1994 [1] and International Organization for Standardization (ISO)/TR 5460-1985(E) [3] depicts the rotation of a part around its datum axis while a dial gauge measures the variations in the feature’s surface. These standards do not address the evaluation of runout using modern measurement technologies using discrete point clouds that dominate the metrology industry. This research presents a comprehensive methodology for evaluating runout tolerance using discrete data that closely replicates the requirements specified by the ASME and ISO standards. This work builds upon previous work by the authors, reported in Turek et al. [9] and presents a comprehensive methodology for evaluating circular and total runout for flat, tapered, and cylindrical features using discrete data. The methodology was tested using simulated datasets and the analysis reaffirmed the results reported in Turek et al. [9] regarding the choice of minimum circumscribing cylinder as the preferred datum axis evaluation technique. Subsequently, the approach presented in this paper was applied to discrete data acquired from two manufactured parts. The results obtained were compared with traditional runout measurements acquired with a dial gauge. This comparison required the filtering of the discrete data to compensate for the finite radius of the dial gauge tip, and led to the development of a novel filtering technique to appropriately compare results. The results using the filtered data closely match the results obtained from the dial gauge, confirming the accuracy of the presented runout assessment algorithms. This work presents a first step in assessing runout using discrete data and justifies the use of modern metrology techniques in runout evaluation.     

Extension of a Current Continuum-Level Material Model for Soil into the Low-Density Discrete-Particle Regime

In this article, an attempt is made to construct a soil-material model which can be used over a wide range of soil densities. To construct such a model, an existing purely continuum-type soil material model (used in the high-density regime), within which the granular structure of the soil is neglected, is combined with an existing discrete-type soil material model (used in the low-density regime) within which soil is treated as an assembly of interacting particles. In order to enable it to be used in conventional transient, nonlinear dynamics, and finite element analyses, the new soil material model is cast using a continuum-type framework. Thus, while in the low-density regime soil behavior is fully dominated by the discrete-type soil-material model, soil has been treated as a continuum constituent properties of which are governed by particle geometrical parameters and particle-particle interaction laws. To demonstrate the utility and fidelity of the new soil material model, a series of uniaxial strain computational tests involving rectangular, parallelepiped-shaped soil-slug normal impact onto a rigid, fixed, flat surface is carried out. While these tests are of a one-dimensional character, they are generally considered as being representative of the loading and deformation histories experienced by mine-blast-ejected soil during its impact with the target structure. The results obtained using the newly proposed soil material model, in the low-density regime, are found to be fully consistent with their discrete-particle modeling and simulation counterparts, suggesting that the new model can be used in transient nonlinear dynamics, finite element simulations involving low-density soil.