Dichlorodimethylsilane as an anti-stiction monolayer for MEMS: acomparison to the octadecyltrichlorosilane self-assembled monolayer

This paper presents a quantitative comparison of the dichlorodimethylsilane (DDMS) monolayer to the octade-cyltrichlorosilane (OTS) self-assembled monolayer (SAM) with respect to the film properties and their effectiveness as anti-stiction coatings for micromechanical structures. Both coatings have been evaluated in several ways, including atomic force microscopy (AFM), contact angle analysis (CAA), work of adhesion by cantilever beam array (CBA) technique and coefficient of static friction using a sidewall testing device. While water and hexadecane contact angles are comparable, the DDMS coated microstructures exhibit higher adhesion than OTS coated ones. Furthermore, coefficient of static friction data indicate that the DDMS films are not as effective at lubrication as the OTS SAMs are, although both exhibit much improvement over chemical oxide. However, AFM data show that the samples which receive DDMS treatment accumulate fewer particles during processing than those which receive the OTS SAM treatment. The thermal stability of the DDMS film in air far exceeds the OTS SAM, as the DDMS remains very hydrophobic to temperatures upwards of 400°C     

Ring perception in organic structures: A new algorithm for finding SSSR

An original algorithm for ring perception in organic chemical structures is presented. It divides rings into two classes to be separately investigated, simplifies the molecular graph and, without finding all possible cycles, efficiently identifies only the SSSR, as required by the synthesis planning program Lilith of which it is a part. Its application to some organic structures and to particular ring systems is reported. An evaluation of speed is included.     

Investigation of anti-stiction coating for ohmic contact MEMS switches with thiophenol and 2-naphthalenethiol self-assembled monolayer

Anti-stiction coating with a conductive self-assembled monolayer (SAM) formed by π-conjugated bonds was investigated for ohmic contact microelectromechanical system (MEMS) switches with low-load contacts. SAMs of thiophenol (C₆H₅SH, TP) or 2-naphthalenethiol (C₁₀H₇SH, 2NT) were coated on Au samples with different surface roughness to investigate the effects of the surface asperities on the adhesion force and contact resistance. The adhesion force was measured using a silicon tipless cantilever in the relative humidity range of 10-85% and the contact resistance was measured in the contact force range of 0-70 μN using a conductive tipless cantilever coated with Au for the SAM coated samples and compared with those for a Au sample surface. The adhesion force measurements indicate that the TP and 2NT coatings can prevent a liquid meniscus from forming on device surfaces due to their hydrophobic character caused by the protruding aromatic group. In addition, it was confirmed that these coatings could reduce van der Waals forces more than Au coating. Contact resistance measurements revealed that an electric current begins to flow with smaller contact force for TP and 2NT coated samples than for Au coated samples. The measured contact resistances of the SAM and Au coated samples were comparable. Based on these results, SAMs of TP and 2NT have excellent potential as anti-stiction coating for MEMS switch contacts.     

Design of novel compact anti-stiction and low insertion loss RF MEMS switch

A novel torsional RF MEMS capacitive switch design on silicon substrate is presented. The optimized switch topology such as reduction in up-state capacitance results in insertion loss better than ?0.1 dB till 20 GHz. Off to on state capacitance ratio is also improved by 18 fold and isolation is better than ?43 dB at 9.5 GHz. The achieved on state return loss is ?38 dB as compared to ?21 dB at 9.5 GHz. An optimized reduction in contact area and use of floating metal layer increases the switching speed from 56 to 46 μsec. It also increases the switch reliability by alleviating the stiction.     

A new basis for PHT-splines

PHT-splines (polynomials splines over hierarchical T-meshes) are a generalization of B-splines over hierarchical T-meshes which possess a very efficient local refinement property. This property makes PHT-splines preferable in geometric processing, adaptive finite elements and isogeometric analysis. In this paper, we first make analysis of the previously constructed basis functions of PHT-splines and observe a decay phenomenon of the basis functions under certain refinement of T-meshes, which is not expected in applications. We then propose a new basis consisting of a set of local tensor product B-splines for PHT-splines which overcomes the decay phenomenon. Some examples are provided for solving numerical PDEs with the new basis, and comparison is made between the new basis and the original basis. Experimental results suggest that the new basis provides better numerical stability in solving numerical PDEs.     

Output modifier adaptation with filter-based constraints

Modifier adaptation (MA) and output modifier adaptation (MAy) are iterative model-based real-time optimization (RTO) algorithms that have the proven ability to drive plants to their optimal operating condition upon convergence despite disturbances and modeling uncertainty, provided the model at hand satisfies model adequacy conditions. But there is no guarantee that constraints are satisfied before convergence. In this article, an improvement of the formulation of MA and MAy is proposed that is proven to bring significant improvements w.r.t. these two limitations – model adequacy and feasibility of iterates. While standard MA or MAy suggests to perform optimization and filtering sequentially, it is proposed to integrate the input filtering stage in the modified model-based optimization problem by means of additional filter-based constraints. The corresponding approach, labeled “KMAy”, is (i) proven to preserve constraint qualification despite additional constraints, (ii) proven to preserve the property of MA methods to converge to the true plant optimal inputs, (iii) proven to significantly relax the model adequacy condition - leading it to be independent of the constraints of the optimization problem, (iv) shown to increase the chances of converging from the safe side of the plant constraints and (v) shown to support the choice of input filtering, instead of output or modifier filtering, if the input filter is appropriately chosen. A method for the automatic selection of the largest filter gain with the five aforementioned assets, while minimizing the filter-induced conservatism, is also proposed. The performances of KMAy with and without adaptive gain are successfully illustrated by means of the optimization of a benchmark simulated chemical reactor.     

A new computer system for education

Advances in available computer and data communications technology are not, in general, immediately available in the classroom and laboratory. This paper gives details of a computer board which uses state-of-the-art technology to create a system which is useful as a classroom tool as well as a research and laboratory instrument. The new system encourages a hands-on approach by making available to the user all the appropriate signals. The board utilizes a Motorola 68030 microprocessor augmented with a 68882 floating point unit (FPU) to provide the compute power of the system. The system also has 8 MB of dynamic RAM combined with a large cache, as well as 128 KB of read-only memory. In addition, the system has SCSI and VME bus interfaces, an Ethernet interface, two RS232 terminal connections, and two parallel/timer ports for project implementation. The new computer board is host independent and thus can operate as a stand alone system.

Researchers in electrical engineering can benefit from the facilities provided, as well as engineers working in microprocessor design and implementation, programming, data networking, operating systems, instrumentation and computer interfacing areas. In this paper, we cover topics which utilize many features of the system, such as digital signal processing, digital control and image processing.     

A new model for large memories

In this paper a new Memory Model of Computation (CMM) is introduced. In CMM, a RAM processor accesses a memory ofx cells in log x time. In fact, the usual assumption of the RAM model, that all memory cells are accessed in constant time, becomes impractical asx increases. With a very simple modification of the boolean circuits of the memory, CMM makes it possible to access in constant time, a memory cell consecutive to another already accessed cell. Problems of sizen requiring time T(n) in the RAM model can be solved in CMM with a multiplicative factor O(log x) in time complexity. Ad hoc algorithms are instead designed for other basic problems such as searching and sorting.     

A new model for selfish routing

In this work, we introduce and study a new, potentially rich model for selfish routing over non-cooperative networks, as an interesting hybridization of the two prevailing such models, namely the KPmodel [E. Koutsoupias, C.H. Papadimitriou, Worst-case equilibria, in: G. Meinel, S. Tison (Eds.), Proceedings of the 16th Annual Symposium on Theoretical Aspects of Computer Science, in: Lecture Notes in Computer Science, vol. 1563, Springer-Verlag, 1999, pp. 404–413] and the Wmodel [J.G. Wardrop, Some theoretical aspects of road traffic research, Proceedings of the of the Institute of Civil Engineers 1 (Pt. II) (1952) 325–378].     

A new corrective scheme for SPH

A new corrective scheme for Smoothed Particle Hydrodynamics (SPH) is introduced which greatly improves its accuracy, particularly in regions of particle deficiency or when particles are irregularly distributed. The scheme is based on the Taylor expansion of the SPH kernel estimates. The corrective equations are derived up to the second derivative in an arbitrary number of dimensions. Test applications for the new scheme include the interpolation of functions and the numerical solution of the heat equation in one and two dimensions.     

A new approach for workshop design

In this paper we solve a combined group technology problem with a facility layout problem (FLP). This new approach is called T-FLP. We have developed a hybrid algorithm containing three main steps. The first one, called MPGV (Machine Part Grouping with Volume) is a decomposition method that can create families of product and machine groups based on a volume data matrix. The second one consists on assigning machines to fixed locations, using as a constraint, the solution of the MPGV. This problem is solved as a Quadratic Assignment Problem (QAP). In the third step, we make a global evaluation of all the solutions. A loop on cells is performed using a minimum and maximum number of cells. This loop can choose the appropriate number of cells based on the best solution of a global evaluation. The hybrid algorithm is implemented with two different rules for taking into account the constraint of the MPGV solution. This has generated two methods called YMAY1 and YMAY2. In the MPGV we use a data oriented genetic algorithm. The QAP is solved with an Ant Colony Optimization mixed with a Guided Local Search (ACOGLS). This method has been used to solve a real industrial case. For estimating the efficiency of our method, we have compared our results with an optimal solution obtained by complete enumeration (an exact method).     

A new approach for delay-constrained routing

Delay-constrained routing protocols are used to find paths subject to a delay constraint while efficiently using network resources. Many of the delay-constrained routing protocols that have been proposed in the literature give priority to cost minimization during the path computing process. With this approach, paths with end-to-end delays too close to the delay constraint are obtained. We believe that such paths are prone to delay constraint violations during load variations in the network. The root of such violations can be found in the imprecision of delay information during the routing process. In this paper, we propose a new approach for delay-constrained routing which captures the tradeoff between cost minimization and the risk level regarding to the delay constraint. We propose a protocol called Parameterized Delay-Constrained Routing protocol that implements our approach using a simple and efficient parameterized selection function. We expand this work to multicasting by proposing three new delay-constrained multicast routing protocols based on the source (Naïve), destination (Greedy) and mixed multicast routing techniques. Our simulations show that our protocols produce paths and trees which are stable, less risky and suitable for various network conditions.     

A new matrix test for randomness

Let ${{\mathcal S}}$ be one of the two multiplicative semigroups: M × M Boolean matrices, or the semigroup of M × M matrices over the field GF(2). Then for any matrix ${A\in {\mathcal S}}$ there exist two unique smallest numbers, namely the index and period k, d, such that A ^k  = A ^k+d . This fact allows us to form a new statistical test for randomness which we call the Semigroup Matrix Test. In this paper, we present details and results of our experiments for this test. We use Boolean matrices for M = 2, . . . , 5, and matrices over GF(2) of the size M = 2, . . . , 6. We also compare the results with the results obtained by the well-known Binary Matrix Rank Test.     

A new algorithm for stable assignments

A new algorithm for solving stable assignment problems is presented. By using a weight table, the overall situation of a problem is considered. The algorithm can deal with not only the one-to-one type assignments but also multi-function assignments for both equal and unequal sets. Some examples are given to illustrate the algorithm.     

A new convexity measure for polygons

Abstract-Convexity estimators are commonly used in the analysis of shape. In this paper, we define and evaluate a new convexity measure for planar regions bounded by polygons. The new convexity measure can be understood as a "boundary-based" measure and in accordance with this it is more sensitive to measured boundary defects than the so called "area-based" convexity measures. When compared with the convexity measure defined as the ratio between the Euclidean perimeter of the convex hull of the measured shape and the Euclidean perimeter of the measured shape then the new convexity measure also shows some advantages-particularly for shapes with holes. The new convexity measure has the following desirable properties: 1) the estimated convexity is always a number from (0, 1], 2) the estimated convexity is 1 if and only if the measured shape is convex, 3) there are shapes whose estimated convexity is arbitrarily close to 0, 4) the new convexity measure is invariant under similarity transformations, and 5) there is a simple and fast procedure for computing the new convexity measure.