Unconventional Architectures Research Articles

Back-contact perovskite solar cell fabrication via microsphere lithography

Back-contact electrodes for hybrid organic-inorganic perovskite solar cells (PSCs) eliminate the parasitic absorption losses caused by the transparent conductive electrodes that are inherent to conventional sandwich-architecture devices. However, the fabrication methods for these unconventional architectures rely heavily on expensive photolithography, which limits scalability. Herein, we present an alternative cost-effective microfabrication technique in which the conventional photolithography process is replaced by microsphere lithography in which a close-packed polystyrene microsphere monolayer acts as the patterning mask for the honeycomb-shaped electrodes. A comprehensive comparison between photolithography and microsphere lithography fabrication techniques was conducted. Using microsphere lithography, we achieve highly efficient devices having a stabilized power conversion efficiency (PCE) of 8.6%, twice the reported value using photolithography. Microsphere lithography also enabled the fabrication of the largest back-contact PSC to date, having an active area of 0.75 cm2 and a stabilized PCE of 2.44%.

Design of tubular high‐temperature proton exchange membrane fuel cells (HT‐PEM‐FCs): Development, challenges, and perspectives

AbstractFuel cells (FCs) have gained a prominent position in recent years within the scientific community and the energy market as an alternative to mitigate the inherent problems in the energy production based on fossil fuels such as the constant reduction of nonrenewable resources, greenhouse gas emissions, and climate change. The versatility of high temperature (HT) proton exchange membrane (PEM) FCs, together with their high efficiency and potentially better performance compared to their counterparts, makes them an excellent candidate to accelerate the transition to more environmental friendly energy sources and processes. In recent years, notable developments in this technology have been reported, focusing on the cell components in a planar arrangement, which is the predominant design for all PEM‐FCs. Alternative designs are lagging, even though tubular and conical structures can eventually enhance the power density, decrease sealing areas, and reduce fabrication costs. A lack of information regarding the transition between geometries makes the development and evaluation process tedious and challenging for unconventional architectures. This manuscript describes the development of a novel HT‐PEM‐FC, pointing out the challenges faced during component manufacturing and the proposed tubular FC perspectives.

All poly(3,4-ethylenedioxythiophene) organic electrochemical transistor to amplify amperometric signals

Organic Electrochemical Transistors (OECTs) are emerging devices that find applications as sensors because they offer amazing features such as intrinsic signal amplification, low energy consumption, low cost and easy adaptability to new and unconventional architectures. The signal transduction usually exploits a redox reaction as happens in a common amperometric sensor, but the channel of the transistor is able to amplify this signal. This paper aims to thoroughly investigate the amplification of Faradaic currents in OECT sensors that exploit PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate)) as semiconductor material in the channel and electrochemical transducer. The devices were fabricated with different geometries and thicknesses of PEDOT:PSS in order to find the best configuration. The amplification was studied in phosphate buffer solution as electrolyte by determining the OECT transconductance. A thick PEDOT:PSS layer and a high ratio between gate and channel areas ensure the best performance from an electrical point of view. The amplification was also studied while the OECTs work as chemical sensors for the detection of ascorbic acid. The highest gain was observed for the thickest PEDOT:PSS channel and the lowest ratio between the gate and the channel areas. Moreover, the gate voltage has an important effect on the transistor amplification, being the gain highest (of about 2 orders of magnitude) for the lowest gate voltage.

Long-distance WPT unconventional arrays synthesis

Two innovative array concepts are introduced for the design of long-distance Wireless Power Transfer (WPT) radiating systems. The achievable tradeoffs between complexity/cost mitigation and power focusing capabilities of unconventional WPT architectures with respect to state-of-the-art optimal WPT solutions are investigated. To this end, clustered or sparse WPT arrangements are introduced by formulating their syntheses either as excitation or as pattern matching problems then solved by ad-hoc versions of the Contiguous Partition Method and Compressive Sensing algorithms. Selected numerical examples are presented to assess the features and the potentialities of unconventional WPT designs also in comparison with traditional state-of-the-art optimal methods.

Progress and prospect of two dimensional carbon graphdiyne

New materials have been consented as one of the important keys to break through the bottleneck of science and technology. Motivated by this, lots of researchers make efforts to discover or develop new materials in unconventional architectures. In the past two decades, tremendous efforts have been devoted to finding new carbon allotropes such as fullerene, carbon nanotube, and graphene. Different carbon allotropes have been demonstrated by altering the periodic binding motif consisted of sp, sp2 and sp3 hybridized carbon atoms. These carbon materials with great advantages of structure and electronic structure, the practical experiments, displaying many applications in the fields of catalyst, rechargeable battery, solar cell, information technology, gas separation, water purification and electronic device. The theoretical prediction and practical advances in graphdiyne (GDY) discussed here indicate that these new two-dimensional (2D) carbon allotropes are being introduced as next-generation materials in the carbon family.

An integrated approach to vehicle and subsystem sizing and analysis for novel subsystem architectures

The aerospace industry is currently transitioning to More Electric subsystem architectures due to steadily improving electric technologies and the technology saturation of established conventional architectures. For aircraft with such unconventional architectures, the lack of historical information and the presence of increased inter-subsystem interactions create a significant design challenge. These necessitate a greater focus on subsystems design earlier in the design process than typically seen for aircraft with conventional subsystem architectures. At the same time, however, to be suitable for the early design phases, the subsystem analyses must be computationally inexpensive and not require detailed aircraft definition. This work presents an integrated, modular, and tool-independent approach to the sizing and performance analysis of the aircraft and its subsystems, in which inter-dependencies are established between relevant aircraft and subsystem level parameters. The approach allows the assessment of subsystem architectures using vehicle and mission level metrics for a fixed vehicle design, and also the amplified effect of re-sizing the vehicle in accordance with a pre-defined rule-set. The proposed approach was demonstrated through a comparative assessment of a predominantly electric subsystem architecture and a conventional one for a representative single-aisle aircraft. In this assessment, the impacts of changing the form of secondary power extraction, the change in vehicle empty weight, and re-sizing of the vehicle were successively identified.

Comprehensive approach to comparative efficiency evaluation of HPS for helicopters

Purpose – The purpose of the work is to carry out analysis of the possibilities and estimation of electric drive efficiency for rotors of helicopter propulsion systems (PS). Design/methodology/approach – Methodology and comprehensive multidisciplinary technology for efficiency estimation of conventional and unconventional architectures PS on rotorcraft system level at preliminary design phase were developed. Findings – Application of the approach allow to carry out analysis of hybrid (based on gas turbine and piston engines) and full electrical PS for superlight-, light- and medium-size helicopters. Practical implications – It was shown what level of electrical technologies improvement may provide positive effect of the using of hybrid and full electrical helicopter PS of different architectures. Originality/value – Close matching of helicopter and engine design and calculation aspects, as well as possibilities to use the external (experimental) performances of engine components, whole PS and helicopter a...

Isocyanate- and phosgene-free routes to polyfunctional cyclic carbonates and green polyurethanes by fixation of carbon dioxide.

The catalytic chemical fixation of carbon dioxide by carbonation of oxiranes, oxetanes, and polyols represents a very versatile green chemistry route to environmentally benign di- and polyfunctional cyclic carbonates as intermediates for the formation of non-isocyanate poly-urethane (NIPU). Two synthetic pathways lead to NIPU thermoplastics and thermosets: i) polycondensation of diacarbamates or acyclic dicarbonates with diols or diamines, respectively, and ii) polyaddition by ring-opening polymerization of di- and polyfunctional cyclic carbonates with di- and polyamines. The absence of hazardous and highly moisture-sensitive isocyanates as intermediates eliminates the need for special safety precautions, drying and handling procedures. Incorporated into polymer backbones and side chains, carbonate groups enable facile tailoring of a great variety of urethane-functional polymers. As compared with conventional polyurethanes, ring-opening polymerization of polyfunctional cyclic carbonates affords polyhydroxyurethanes with unconventional architectures including NIPUs containing carbohydrate segments. NIPU/epoxy hybrid coatings can be applied on wet surfaces and exhibit improved adhesion, thermal stability and wear resistance. Combining chemical with biological carbon dioxide fixation affords 100% bio-based NIPUs derived from plant oils, terpenes, carbohydrates, and bio polyols. Biocompatible and biodegradable NIPU as well as NIPU biocomposites hold great promise for biomedical applications.

Architecture and applications for an All-FPGA parallel computer

The Reconfigurable Computing Cluster (RCC) project has been investigating unconventional architectures for high end computing using a cluster of FPGA devices connected by a high-speed, custom network. Most applications use the FPGAs to realize an embedded System-on-a-Chip (SoC) design augmented with application-specific accelerators to form a message-passing parallel computer. Other applications take a single accelerator core and tessellate the core across all of the devices, treating them like a large virtual FPGA. The experimental hardware has also been used for basic computer research by emulating novel architectures. This article discusses the genesis of the over-arching project, summarizes results of individual investigations that have been completed, and how this approach may prove useful in the investigation of future Exascale systems.

Switching control of resistive switching devices

Switching current control plays a critical role in the operation of resistive switching devices. Both on-state resistance and maximum reset current show strong dependence on the current limit during set switching. The dependence in unipolar switching devices can be explained by the power-driven nature of reset and dynamic competition between set and reset forces. Effective switching control improves device characteristics including uniform resistance distribution and low reset current. However, it also presents challenges for the choice of selection devices and the feasibility of unconventional architectures for resistive switching devices.

Unconventional Parallel Architectures

Looking at the history of computing one can find out that the designers repeatedly addressed specialized ( non von-Neumann ) architectures which provide comparatively high performance in some specific applications. Suffice it to say that one of the earliest supercomputer projects, the S. Unger's system destined for pattern recognition was a rectangular array of interconnected simple processing modules. At the beginning of 60s, an original conception of a reconfigurable cellular structure called Homogeneous Computing Medium was suggested in Russia. It is worth to note that recently this promising idea found its continuation in the MIT project Raw based on newest technology. Great consideration was given to associative memories and fine-grained SIMD architectures. Thus, in the late 80s the massively parallel fine-grained systems DAP (S. Reddaway) and CM (D. Hillis) made at the market a grave competition to the supercomputers of conventional architecture. In 90s, powerful microprocessors of essentially traditional architecture occupied the dominating position due to the rapid progress in microelectronics and the corresponding dramatic decrease of component cost. Nevertheless, the well-known rule remains valid: taking into account specific features of a given class of problems and computational methods, one can get great improvement in performance and cost/performance factor when using application specific unconventional architectures. After the publishing of the CFP for this Special Issue of SCPE, we received 10 papers submitted by 19 authors from various countries. In the present Issue five papers are being published which obtained the highest rating from reviewers. These papers introduce some interesting trends in the development of unconventional parallel computing systems. The first paper Reaction-Diffusion and Excitable Processors: a Sense of Unconventional by Andrew Adamatzky is devoted to a very important and prospective subject of parallel data processing in chemical media. So-called architecture-less processors are discussed where a layer of an oscillating reaction is considered a massively parallel system each elementary processor of which is represented by a micro-volume reactor. Cellular automata are used as a computational model. The author demonstrates that excitable media can constitute universal massively parallel computing devices. In the second paper A Scalable Multiprocessor for Real-Time Signal Processing Applications Hans Eberle and Daniel Scherrer present a new platform for real-time processing of continuous data streams such as audio, video or graphical data. To overcome the limitations of existing DSPs the authors designed a flexible and scalable communication infrastructure Switcherland which guarantees data transfer with bounded latencies. The advantages of suggested multiprocessor provide for a wide range of applications in real-time signal processing. Bernard Girau in his paper Conciliating Connectionism and Parallel Digital Hardware presents an original paradigm of digital hardware implementation of neural computations, Field Programmable Neural Arrays (FPNAs). Both theoretical and practical aspects are discussed including the mapping of FPNAs into FPGAs. It is shown that the suggested FPNA framework results in efficient fine-grained reconfigurable parallel hardware. Bertil Schmidt and Manfred Schimmler describe in their paper KPROC—an Instruction Systolic Architecture for Parallel Prefix Applications a highly parallel architecture with 1024 floating-point processors on a single chip (at 0.25 micron CMOS technology). These processors constitute an instruction systolic array implementing parallel prefix computation. It is shown that many important applications can take advantage of the suggested model. Examples are discussed from different areas such as image processing, long argument arithmetic, etc. Finally, researchers from Computer Technology Institute (Patras, Greece) C. Konstantinopulos, A. Svolos, D. Serpanos, and D. Maritsas in the paper The Effect of Interword Connectivity in Associative Processing bring forward an important development of associative processors. They introduce an asssociative memory with a single-stage hypercube network interconnecting the memory words. Significant performance improvement of this architecture is demonstrated through the analysis of various real applications. We wish to express our deep gratitude to the reviewers (D. Sima, F. Vajda, K. Grosspietsch, P. Szolgay, E. Luque, A. Pimentel, D. Ortega, M. Valero, O. Bandman, V. Malyugin, P. Keresztes, M. Amamiya, Y. Fet, R. Moore, K. Waldschmidt, S. Theodoridis, L. Ricci, A. Ripoll, S-W. Lee, J-L. Gaudiot, V. Estigneev, S. Sedukhin) who helped us to select the best papers and to improve the quality of the accepted. Guest Editors Yakov Fet and Peter Kacsuk

BLOCK ADJUSTMENT WITH ARRAY AND VECTOR PROCESSORS

AbstractThe paper discusses some hardware and software developments in mainframe computers and their effects on aerial triangulation block adjustment programs. The results of test runs on two modern computers with unconventional architectures are given and comparisons are made with run times on more conventional serial type computers.

Functional decomposition on multi-micro-processor systems

Increased sophistication ofpresent microprocessors and other l.s.i. devices allows creation of unconventional computer architectures. The work reported here is part of a project concerned with the application of multi-processor architectures to business data processing. An application is considered as a number of interacting functional units. The operation of a system consists of the allocation of functional units to processing units at execution time. A processing unit contains a microprocessor, r.o.m., r.a.m., firmware and interface devices for communication with adjacent processing units and peripherals. Basic modes for interconnection of processing units are discussed. More generalized cellular structured architectures are considered and software problems examined.