Non-trivial Functionality Research Articles

Real-time monitoring of polarization state deviations with dielectric metasurfaces

We propose and experimentally demonstrate a dielectric metasurface that allows monitoring of polarization deviations from an arbitrary elliptical input anchor state simply by tracking in real-time the output ratio between the powers of horizontal and vertical components after the metasurface. Importantly, this ratio can be enhanced corresponding to increased responsivity. Such nontrivial functionality is achieved by designing binary metasurfaces that realize tailored nonunitary and chiral polarization transformation. We experimentally demonstrate the operation at telecommunication wavelengths with enhanced responsivity up to 25 for various anchor states, including the strongly elliptical and circular. We also achieve the uncertainty of deviation measurement that is significantly better than the fundamental limit for nonchiral metasurfaces.

DESIGNING DISTRIBUTED AUTOMATIC SOFTWARE UPDATE SYSTEM

This article offers the reader a practical guide to the design and development of a distributed client-server system designed to perform automatic software updates using the example of non-trivial functionality. For comparison, examples of existing systems and solutions used to perform software updates are given and justifications for their functional unsuitability in the given circumstances are provided.

All-angle Negative Reflection with An Ultrathin Acoustic Gradient Metasurface: Floquet-Bloch Modes Perspective and Experimental Verification

Metasurface with gradient phase response offers new alternative for steering the propagation of waves. Conventional Snell’s law has been revised by taking the contribution of local phase gradient into account. However, the requirement of momentum matching along the metasurface sets its nontrivial beam manipulation functionality within a limited-angle incidence. In this work, we theoretically and experimentally demonstrate that the acoustic gradient metasurface supports the negative reflection for all-angle incidence. The mode expansion theory is developed to help understand how the gradient metasurface tailors the incident beams, and the all-angle negative reflection occurs when the first negative order Floquet-Bloch mode dominates inside the metasurface slab. The coiling-up space structures are utilized to build desired acoustic gradient metasurface, and the all-angle negative reflections have been perfectly verified by experimental measurements. Our work offers the Floquet-Bloch modes perspective for qualitatively understanding the reflection behaviors of the acoustic gradient metasurface, and the all-angle negative reflection characteristic possessed by acoustic gradient metasurface could enable a new degree of the acoustic wave manipulating and be applied in the functional diffractive acoustic elements, such as the all-angle acoustic back reflector.

IsBF: Scalable in-packet bloom filter based multicast

Bloom filter (BF) based forwarding was proposed recently in several protocol alternatives to IP multicast. Some of these protocols avoid the state in intermediate routers and leave the burden of scalability management to the multicast source and end-hosts. Still, the existing BF-based protocols have scalability limitations and require explicit network management as well as non-trivial functionality from the network components. In this work we address the scalability limitations of the BF-based forwarding protocols by partitioning end-hosts into clusters. We propose several algorithms to do the partitioning so as to decrease the overall traffic in the network. We evaluate our algorithms in a real Internet topology, demonstrating the ability of the proposed design to save up to 70% of traffic volume in the large-scale topology for big groups of subscribers, and up to 30% for small groups.

AN ANALYTICAL EXPRESSION FOR THE DISPERSION COEFFICIENT IN POROUS MEDIA USING CHANG'S UNIT CELL

Mathematical modeling of transport phenomena in hierarchical systems is often carried out by means of effective medium equations resulting from upscaling techniques. For the case of convection and diffusion taking place at the pore scale, the upscaled model is expressed in terms of a total dispersion tensor, which encompasses the essential features from the microscale. Several theoretical and experimental works have evidenced that the dispersion coefficient follows a power-law dependence with the particle Peclet number. In this work, we show that such functionality can be derived analytically using the method of volume averaging with Chang's unit cell. Our derivations lead to an expression for the dispersion coefficient that reduces to the classical result by Maxwell under purely diffusive conditions. Interestingly, the dispersivity is found to follow a nontrivial functionality with the particle Peclet number. The predictions from our analytical expression are compared with those obtained by solving the same closure problem in periodic unit cells showing, in general, good agreement, especially for homothetic unit cells.

Study on the cascadability of a SOA-assisted Sagnac switch pair

The ability of the SOA-assisted Sagnac switch to be cascaded in a pair scheme where the output from the transmission port drives directly the subsequent control terminal is investigated and demonstrated. For this purpose an efficient model that simulates the behavior of the SOA employed in each one of these interferometric arrangements is suitably applied to describe their concatenated setup. By conducting an extensive theoretical treatment the impact of the involved critical operational parameters on the defined quality metrics is thoroughly analyzed and assessed enabling to provide useful design rules for their proper selection and the achievement of enhanced performance. The two switches in tandem are a replica of each other if the leading one is driven as well as serially triggers its trailing counterpart with the proper amount of energy so that both SOAs are biased around the same saturation point. In this manner the formed chain is practically realizable and its contrast ratio can be optimized by means of the second module it comprises of. The outcome of this work can facilitate the implementation of larger, multistage switch fabrics and combinatorial circuits of non-trivial logical functionality in which this kind of interconnected architecture is the basic building block.

Performance investigation of semiconductor optical amplifier-based ultrafast nonlinear interferometer in nontrivial switching mode

The feasibility of operating the semiconductor optical amplifier (SOA)–based ultrafast nonlinear interferometer (UNI) in nontrivial switching mode is methodically investigated and demonstrated. For this purpose, a comprehensive model that simulates the dynamical behavior of an SOA subject to an ultra-high-speed pseudorandom binary sequence is appropriately adapted to the case of the specific configuration. By undertaking a detailed theoretical treatment, the impact of the most important SOA parameters on the fully loaded Q-factor is thoroughly analyzed and assessed, enabling us to extract useful design rules for their proper selection so as to ensure enhanced error-free performance at the desired output port of the considered interferometric arrangement. The outcome of this effort may assist the study and implementation of all-optical circuits and subsystems of nontrivial functionality, in particular with feedback, in which the UNI employing a SOA as the nonlinear element is the core logical module.

The Design of an Allo-Optical Packet Switching Network

Recent advances in the all-optical signal processing domain report high-speed and nontrivial functionality directly implemented in the optical layer. These developments mean that the all- optical processing of packet headers has a future. In this article we address various important control plane issues that must be resolved when designing networks based on all-optical packet-switched nodes.

Realizing the vision for web services: Strategies for dealing with imperfect standards

Organizations considering the adoption of the web services framework for their Information Technology (IT) applications are confronted with a period of technological ferment, as standards for supporting non-trivial business process functionality are not yet in place. Evolving standardization poses challenges in the form of inter-temporal dependencies as organizations' conformance to the standards that emerge in the future is contingent on their current design choices that need to be made ex-ante without complete information of how standards will evolve. At the same time, there are significant early-mover benefits to be gained by executing an IT strategy using web services as a cornerstone. This paper draws upon coordination theory to develop a conceptual framework outlining three approaches for organizations to deal with changing standardization regimes: (a) The dependencies across components, conforming to different standardization regimes, are continually bridged through intermediary services (e.g., using a protocol adapter that translates to an unanticipated emergent standard), (b) The dependencies across components are minimized through loose coupling so that standardization regime changes for any component have a minimal impact on other components (e.g., encapsulating the functionality susceptible to design change into a module with abstract interfaces), and (c) The impacted components are rapidly reconfigurable as and when standardization regime changes (e.g., by building in "extension" features into applications). The risk for organizations investing in web services can be further managed by mechanisms such as organization's attention to signals from the periphery, undertaking low-risk experiments to learn in different areas, and bricolage-like improvisations of their legacy components at hand.

All-optical signal Processing and applications within the esprit project DO/spl I.bar/ALL

This paper reviews the work performed under the European ESPRIT project DO/spl I.bar/ALL (Digital OpticAL Logic modules) spanning from advanced devices (semiconductor optical amplifiers) to all-optical modules (laser sources and gates) and from optical signal processing subsystems (packet clock recovery, optical write/store memory, and linear feedback shift register) to their integration in the application level for the demonstration of nontrivial logic functionality (all-optical bit-error-rate tester and a 2/spl times/2 exchange-bypass switch). The successful accomplishment of the project's goals has opened the road for the implementation of more complex ultra-high-speed all-optical signal processing circuits that are key elements for the realization of all-optical packet switching networks.

Computer support of architectural sketch design: a matter of simplicity?

Computer support of architectural sketch design persistently remains a topic of research, rather than a reality of practice. The inherent complexity of creative design may be one reason; the alienation of designers by technology another. The author suggests that to avoid alienation we should develop small, affordable systems, as simple and natural to use as ordinary word processors. An attempt in that direction is the MacAlex system, currently under development as part of a project with the aim of investigating how formalized Alexander patterns could be utilized in knowledge-based computer support of sketch design. The paper is a description of an initial user-interface design for MacAlex and its implementation as an empty-shell prototype. On that background, conditions are listed under which “perceived simplicity” of sketch design systems would seem reconcilable with their nontrivial functionality.