Low-cost Structure Research Articles

Realization of enhanced sound-driven CNT-based triboelectric nanogenerator, utilizing sonic array configuration

Triboelectric nanogenerators have been emerged as the most promising mechanical energy harvesters, during last few years. Here, a sonic triboelectric nanogenerator with 7-fold enhanced output power is reported, in which carbon nanotubes are utilized to increase the electrode's effective surface area. To improve the efficiency we have taken advantage of acoustic wave localization in a sonic array. For this purpose, first we have studied an array of periodic acoustic scatterers by simulation. Then, we have designed a 1-D phononic crystal consisting of five steel slabs standing in air medium, which leads to resonance of incident acoustic wave at f = 4.34 kHz. We implemented the design, but replaced the middle scatterer by triboelectric nanogenerator. An enhancement factor of about 4 has been measured for the output voltage of the sonic nanogenerator at f = 4.24 kHz, when it is embedded in the sonic array. Also, power enhancement factor of 7-fold has been achieved (Pout≈4 μW/m2), benefiting from the applied sonic cavity. The measured resonance frequency and enhancement factor are in acceptable agreement with the simulation results. The presented enhanced energy harvesting configuration proposes a compact and low cost structure, which allows parallel energy harvesting, and seems promising for realizing sonic harvesters.

A Simple Technique for Triangular Waveform Generation based on a Dual-Polarisation Modulator

A new microwave photonic topology for generating a triangular waveform is presented. The concept is based on incoherent summation of two intensity modulated optical signals to generate the first- and third-order harmonic frequency components with the same amplitude and phase as that of an ideal triangular waveform. The proposed triangular waveform generator has a very simple and low-cost structure as it only requires the Mach Zehnder modulator in a conventional fiber optic link to be replaced by an integrated dual-polarization modulator driven by two 90° phase difference RF signals. It also has a widely tunable repetition rate, low insertion loss, and a stable performance. Experimental results demonstrate a triangular waveform with a tunable microwave-frequency repetition rate and a root mean square error value of <;0.049 when comparing with an ideal triangular waveform. The stability of the proposed triangular waveform generator is also examined experimentally.

Analysis and study on the thermodynamic performance of S-CO2 simple Brayton cycle

The S-CO2 Brayton cycle system has many characteristics such as low cost and compact structure, and is one of the hotspots in the fields of waste heat utilization, new energy and so on. In this paper, a mathematical model of the S-CO2 simple Brayton cycle is constructed, and the cyclic characteristics are analysed. The relationship between the component parameters of the system and the calculation parameters of the cycle such as the cycle efficiency and the output net work are obtained under the design conditions. Meanwhile, calculation models of turbine and compressor under off-design conditions are established, and the characteristics of the whole cycle are analyzed. Thus, the characteristics of off-design conditions of the simple cycle are obtained. This study provides some reference for the related research of the S-CO2 Brayton cycle and the practical engineering application.

Continuous input-current buck-boost DC-DC converter for PEM fuel cell applications

This paper proposes a buck-boost converter topology with continuous input-current capability for proton exchange fuel cells (PEMFC) systems. The continuous input-current feature of the converter contributes to maintain the PEMFC life-time, which is in sharp contrast with traditional buck-boost converters whose input currents damage the PEMFC and reduce the efficiency. Moreover, this converter offers the main advantages found in traditional topologies, such as the Cuk or the SEPIC converters, using a reduced number of electronic components. In particular, the topology features buck-boost conversion range capability, low input-current ripple, and a simple low-cost structure. A detailed analysis that encompasses steady state analysis, dynamic modelling, stability analysis, control and experimental results are provided.

Analysis of Winding Forms for Bearingless Flux-Switching PM Motor with U-core Stator Laminations

Due to low-cost and magnet-free rotor structure, bearingless flux-switching permanent magnet motors (BFSPMs) are more applicable to high-temperature and/or disposable applications. A BFSPM with U-core stator laminations is investigated in this paper. First, the operational principle is analyzed in accordance with the influence of winding connection manners on torque and radial forces, and then the basic winding arrangement for torque windings and radial force windings is determined. The mathematical models of torque and radial forces are derived based on the basic winding arrangement. Followed by that, a method to select winding terminal connection manners is proposed by taking into account control scheme and power inverter topologies. A promising terminal connection is found from three possible candidates and a detailed current model for torque and radial force control are given for the promising winding forms. Finally, relevant electromagnetic properties of the motor are verified and analyzed by finite element analysis.

Dimensional Precision Research of Wax Molding Rapid Prototyping based on Droplet Injection

The traditional casting process is complex, the mold is essential products, mold quality directly affect the quality of the product. With the method of rapid prototyping 3D printing to produce mold prototype. The utility wax model has the advantages of high speed, low cost and complex structure. Using the orthogonal experiment as the main method, analysis each factors of size precision. The purpose is to obtain the optimal process parameters, to improve the dimensional accuracy of production based on droplet injection molding.

A New Sensitive Excitation Technique in Nondestructive Inspection for Underground Pipelines by Using Differential Coils

In general, a magnetic flux leakage (MFL) pipeline inspection gauge (PIG) has been applied to nondestructive testing for investigating ferromagnetic materials, such as underground gas pipelines. Although MFL PIG is efficient to the inter-city large-scale pipelines, it is hard to apply to small-size pipelines that are usually installed in the city, because the permanent magnet for MFL PIG is too big and heavy to operate inside the small pipe. The strong adhesive magnetic force of permanent magnet to the pipe wall also prevents the usage of MFL PIG in small pipelines. In this paper, we propose a new technology of nondestructive inspection by using a differential coil, which is easy to be manufactured with lightweight, low cost, and simple structure for operating inside the underground pipelines. Comparing with the conventional permanent-magnet MFL PIG, the results of the proposed system could also maximize the detection sensitivity of defect signals and minimize the magnetic adhesive force on the pipe wall simultaneously.

Compact diffraction grating laser wavemeter for cold atom experiments

We present an innovative and practical scheme of building a miniaturized wavemeter, with the advantages of low cost, high reliability and simple structure. Through a calibration test by a 780 nm external cavity diode laser (ECDL), the results show that our system gets a wavelength resolution of better than 1 pm, measurement accuracy of better than 2 pm (corresponding to a frequency of 1 GHz), and a measurement range of 8.5 nm. Finally, the multi-mode comparison test between our system and a commercial spectrum analyzer further indicates the high-precision, miniaturization and low cost of the proposed system, which shows that it is particularly suitable for ECDL and atom cooling and trapping experiments. The system design, experimental results and conclusions are of definite significance as a fine reference for other ranges of wavelength.

Wide Band Patch antenna using Defect Ground Structure Optimizing by Genetic Algorithm

The patch antenna is widely used in our life for a lot of its strong points as a low cost, easy and simple fabricated structure, and a code characteristic in radiation profile. But the narrow bandwidth is, however, the main drawback of a microstrip patch antenna. In this paper the bandwidth of a patch antenna is improved by using a technique known as defected ground structure (DGS), and the size of the antenna is optimized using genetic algorithm. As a result, we were able to optimize the size of the initial antenna proposed (50mm * 30mm * 1.55mm) and expand the bandwidth of the patch antenna. The final simulated prototype has a size of 26mm * 20mm * 1.55mm which corresponds to a miniaturization rate equal to 76%. In relation to the initial antenna, the antenna generates a bandwidth of 4.54GHz, from 3.58GHz to 8.12GHz, which means that the antenna covers the following technologies: WLAN Wireless Local Area Network, Radio local area Network, Worldwide Interoperability for Microwave Access Wimax, Hiper LAN2.

Integrated Metaheuristic Differential Evolution Optimization Algorithm and Pseudo Static Analysis of Concrete Gravity Dam

A differential evolution-algorithm-based optimum design method is presented for concrete gravity dams under stability, principal stress, and sliding constraints. A gravity dam is a large scale hydraulic structure providing its stability based on weight of concrete volume. Hence, optimization of dam cross-section leads to an economic and low cost structure. For this aim, a general dam section is reconstructed with seven proper horizontal and vertical geometric parameters which take into account all possible cross section shapes. Weight of dam is considered as goal function and the optimization problem of geometric parameters is solved using DE algorithm. The DE algorithm written as a MATLAB code are applied to Four benchmark gravity dams including Middle Fork, Richard, Pine Flat, and Friant. The comparison of DE optimum solutions with real dimension of dams and another optimization method in literature shows the performance of the DE algorithm. In mentioned benchmark dams, there are 26.82%, 30.11%, 25.31%, and 20.93% of weight reduction Compared to real values, respectively. Also, optimization results of DE algorithm are compared with literatures. The comparison shows 3.55%, 5.1%, 19.13% and 12.14% reduction of weight compared to GA and PSOD algorithms, respectively.

MULTISEASONAL TREE CROWN STRUCTURE MAPPING WITH POINT CLOUDS FROM OTS QUADROCOPTER SYSTEMS

Abstract. OTF (Off The Shelf) quadro copter systems provide a cost effective (below 2000 Euro), flexible and mobile platform for high resolution point cloud mapping. Various studies showed the full potential of these small and flexible platforms. Especially in very tight and complex 3D environments the automatic obstacle avoidance, low copter weight, long flight times and precise maneuvering are important advantages of these small OTS systems in comparison with larger octocopter systems. This study examines the potential of the DJI Phantom 4 pro series and the Phantom 3A series for within-stand and forest tree crown 3D point cloud mapping using both within stand oblique imaging in different altitude levels and data captured from a nadir perspective. On a test site in Brandenburg/Germany a beach crown was selected and measured with 3 different altitude levels in Point Of Interest (POI) mode with oblique data capturing and deriving one nadir mosaic created with 85/85 % overlap using Drone Deploy automatic mapping software. Three different flight campaigns were performed, one in September 2016 (leaf-on), one in March 2017 (leaf-off) and one in May 2017 (leaf-on) to derive point clouds from different crown structure and phenological situations – covering the leaf-on and leafoff status of the tree crown. After height correction, the point clouds where used with GPS geo referencing to calculate voxel based densities on 50 × 10 × 10 cm voxel definitions using a topological network of chessboard image objects in 0,5 m height steps in an object based image processing environment. Comparison between leaf-off and leaf-on status was done on volume pixel definitions comparing the attributed point densities per volume and plotting the resulting values as a function of distance to the crown center. In the leaf-off status SFM (structure from motion) algorithms clearly identified the central stem and also secondary branch systems. While the penetration into the crown structure is limited in the leaf-on status (the point cloud is a mainly a description of the interpolated crown surface) – the visibility of the internal crown structure in leaf-off status allows to map also the internal tree structure up to and stopping at the secondary branch level system. When combined the leaf-on and leaf-off point clouds generate a comprehensive tree crown structure description that allows a low cost and detailed 3D crown structure mapping and potentially precise biomass mapping and/or internal structural differentiation of deciduous tree species types. Compared to TLS (Terrestrial Laser Scanning) based measurements the costs are neglectable and in the range of 1500–2500 €. This suggests the approach for low cost but fine scale in-situ applications and/or projects where TLS measurements cannot be derived and for less dense forest stands where POI flights can be performed. This study used the in-copter GPS measurements for geo referencing. Better absolute geo referencing results will be obtained with DGPS reference points. The study however clearly demonstrates the potential of OTS very low cost copter systems and the image attributed GPS measurements of the copter for the automatic calculation of complex 3D point clouds in a multi temporal tree crown mapping context.

Novel all-purpose high-power matching device for energy conversion applications

In this study, a novel all-purpose high-power matching device is proposed to be utilized in energy conversion applications. It is a 6kW matching device with a low-cost structure consisting of three distinct stages that a complementary pair of unity-gain current mirrors has been utilized in each stage to provide appropriate output currents and voltages. The proposed device is the first and only all-purpose high-power matching device reported in the literature that can be widely used in energy conversion systems to minimize the cost of construction and maintenance. For instance, it can be utilized in a hybrid power generation system including different power sources such as photovoltaic array, fuel cell stack and battery to directly couple the power sources to each other. While, in the conventional method, the power sources are connected to a common Direct Current-link bus via several converters that significantly imposes extra cost. A prototype of the matching device has been built, and simulation and experimental results are presented to model its behavior at low and high frequency. To show some applications of the matching device, it is first utilized as an adjustable high-power (Direct Current)/(Direct Current) converter which is widely used in electric/hybrid vehicles. As the second application, a photovoltaic/fuel cell hybrid power generation system equipped with a maximum power point tracking controller has been built, and the matching device has been used as an interface unit to connect in parallel a fuel cell stack to a photovoltaic system.

Preparation of Nano Cu-ZnO/PET Fiber for Antibacterial Application

Polyethylene terephthalate (PET) fiber is applied to clothing, home textiles and other fields because of its low cost, high strength, quick-drying and stable structure, etc. Polyester fiber generally doesn’t have the ability to kill bacteria, and it is a kind of porous material which is conducive to the microbial adhesion and spread of bacteria. In the present study, Cu-ZnO and its antibacterial PET fibers were prepared by sol–gel method and melt spinning, respectively. The structures and compositions of Cu-ZnO were characterized by X-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) spectra. The crystallization and melting behavior of the PET/Cu-ZnO (0.05:1) composites were tested by differential scanning calorimetry (DSC) to determine the temperate of melt spinning. The morphologies and mechanical properties of antibacterial polyester fiber were studied by field emission scanning electron micrographs (FE-SEM) and strength machine, respectively. The antibacterial properties of the samples on E. coli and S. aureus were determined using powder inhibition zones and antibacterial rate. The results show that the fibers exhibited excellent antibacterial activity, it had obvious inhibiting effects on E. coli and S. aureus and the antibacterial rate were both above 90%.

A Model and Experiment Study of an Improved Pendulor Wave Energy Converter

Abstract This paper proposes one improved design of pendulor wave energy converter (PWEC), which integrates a pendulor, two side-walls and a slope to concentrate wave power. The slope guides the incident wave upward, and the wave drives the pendulor to rotate upward. Different from previous pendulors, one end of present pendulor is hinged near the free water surface, and the other end swings upward and downward. The mechanical flapping energy is converted to hydraulic energy by the connected hydraulic pump, and then it is converted to electrical energy. The proposed design is verified by theoretical and model-experimental study. The energy conversion efficiency is estimated by a simple weight-lifting method. Experimental results show that the first level conversion efficiency is averaged at 35% under the condition of wave height 0.18m, wave period 1.11s and pendulor length 0.6m. In short, this system has various advantages including simple, compact, modularized, light-weight and low-cost structure, which can be generally installed on ocean shore, near-shore piles and offshore platform, especially for China sea conditions.

Polarization-dependent surface-enhanced Raman scattering (SERS) from microarrays

The convergence between nanometric sensing (e.g. surface-enhanced Raman scattering – SERS) and lab-on-chip technologies has emerged as a potential revolutionary approach for a variety of “real-world” applications. Surface plasmons (SPs) can be excited on metal interfaces through light coupling to metallic surface gratings. The generation of SPs is a fundamental requirement for SERS. The work reported in this paper demonstrates a versatile procedure to prepare both large area (i.e. one inch2) and microarrays (μarrays) metallic gratings structures capable of supporting SP excitation (and SERS). Laser interference lithography (LIL), either alone or combined with traditional laser photolithography (LPL), was used to generate the periodic patterns. The fabrication procedure was simple, high-throughput, and reproducible, with array-to-array variations in geometrical parameters of less than 5%. Since the basic pattern of the nanostructures was a one-dimensional grating, the polarization anisotropy nature of the substrates was also explored. The use of these polarization-dependent properties to eliminate non-polarization sensitive interferences (e.g. spurious spectral background) was demonstrated. Lastly, the nanostructured gold μarrays were integrated on a chip for SERS detection of ppm-levels of 8-quinolinol, an emerging pharmaceutical contaminant in aquatic systems. A low-cost structure for fluid handling was realized by simply using perforated epoxy membranes. The results demonstrated that the procedure described here is suitable for the generation of simple integrated μarrays for SERS applications in environmental analysis.

Tunable Multimode Fiber Based Filter and Its Application in Cost-Effective Interrogation of Fiber-Optic Temperature Sensors

We present a new tunable all-fiber compact multimode fiber (MMF)-based filter and its applications in fiber sensors. Using the matrix optics approach, we theoretically analyze the transmission characteristics of the tunable filter. The expression of the transmission of the optical filter is the same as that of a regular Mach–Zehnder interferometer (MZI) but with an additional optical phase shift in the sinusoidal function, which makes the MMF-based filter tunable. The phase shift could be changed by properly adjusting a polarization controller where the MMF is simply coiled into. The theoretical result has been verified by our experiment. The proposed tunable filter has been employed for intensity interrogation of a fiber Bragg grating (FBG)-based temperature sensor where the MMF-based filter serves as an edge filter. With the tuning technique, we are able to set the FBG peak to the linear regime of the interference pattern to achieve optimum sensing operation range. By monitoring the optical power changes, it is feasible to obtain information that permits temperature measurement with a simple and low-cost structure.

Supercontinuum Generation in an Ytterbium-Doped Fiber Amplifier With Cascaded Double-Clad Passive Fiber Tapers

Supercontinuum (SC) generation directly from an Ytterbium-doped fiber amplifier (YDFA) has many advantages such as high output power, low splicing loss, and high optical to optical conversion efficiency. However, the output spectrum can only extend to longer wavelength. We report a method to further extend the spectral range of SC generated in an YDFA at short wavelength direction by using cascaded double-clad passive fiber tapers. A 750 ps seed pulse at 1060 nm is amplified to 15.9 W and spectrally broadened from 1000 to 1600 nm in an YDFA system. Using this broadband source to pump cascaded double-clad passive fiber tapers, a 14.1 W SC source is obtained, covering 630 to 2000 nm, which is in an all-fiber and low-cost structure. It is found that, in fiber tapers, especially at the taper waist, the frequency shift rate of solitons increases significantly, and those red-shifted solitons are group-velocity matched to dispersive waves even in the red wavelength region. To our best knowledge, this is the first time there has been generation in tapered double-clad passive fiber.

A new support material for IgG adsorption: Syntrichia papillosissima (Copp.) Loeske

In this presented work, Syntrichia papillosissima (Copp.) Loeske (S. papillosissima) was used as a natural phytosorbent for IgG purification. These moss species were collected for the natural habitat and prepared for IgG adsorption studies by cleaning, drying, and grinding to uniform size. Syntrichia papillosissima samples were characterized by using FTIR and SEM studies. Functional groups of S. papillosissima were identified by FTIR analysis, while surface characteristics were determined by SEM studies. A batch system was used for the adsorption of IgG onto S. papillosissima surface and physical conditions of the IgG adsorption medium were investigated by modifying the pH, IgG concentration and temperature. Maximum IgG adsorption onto S. papillosissima was found to be 68.01 mg/g moss by using pH 5.0 buffer system. Adsorption kinetic isotherms were also studied and it was found that, Langmuir adsorption model was appropriate for this adsorption study. Reusability profile of S. papillosissima was also investigated and IgG adsorption capacity did not decrease significantly after 5 reuse studies. Results indicated that S. papillosissima species have the capacity to be used as biosorbent for IgG purification, with its low cost, natural and biodegradable structure.

A Single-Stage High-Frequency Resonant AC/AC Converter

In many applications, such as large-scale LCD panel backlighting, street lighting, tunnel lighting, etc., an ac/dc light-emitting diode (LED) driver should realize the following three functions at least: power factor correction, multichannel constant current outputs, and galvanic isolation. A novel two-stage multichannel constant current ac/dc LED driver with a low cost and simple structure is proposed in this paper, which is composed of a high-frequency resonant ac/ac converter and as many passive LCL-T resonant rectifiers as the number of the output channels. The high frequency resonant ac/ac converter is focused on in this paper, which converts the ac-line input voltage into high frequency sinusoidal output voltage. First, topology derivation of the single-stage high-frequency resonant ac/ac converter is presented, also the operating principle of it. Then, the steady-state performance of it is completely analyzed, including its input power factor, voltage gain, total harmonic distortion of its output voltage, and its soft-switching condition. Finally, a 130 W prototype is built and the experimental results are given to verify the theoretical analysis.

Nearshore Service Transfers in the EU: Legal and Economic Issues

IntroductionBusiness process offshoring has been growing worldwide in last few years (Tamayo, Huergo, 2015) and rapid development of this industry has been visible in Poland and other Central European countries (ABSL, 2016). It has impacted regional economy's spatial organization which has drastically changed in recent decades (Ledyaeva et al., 2015). Every foreign direct investment (FDI) has significant impact on economic geography of global political and financial networks (Haberly, Wojcik, 2015). The rapid growth of foreign investments in Business Process Outsourcing (BPO), Shared Services Centres (SSC), Research and Development (RD public support; EU standards and stable economy (PAIiIZ, PwC, 2012). Arising from growing organizational and technological ability to coordinate a relocated set of operational tasks, offshore service transfers enabled many firms to integrate their business processes into a global web of activities (Levy, 2005). There are various factors that can facilitate such multinational corporate transformations, through which many companies can achieve lower cost structure that may bring new revenue opportunities, so as other business advantages (Farrell, 2005; Lisin and Strielkowski, 2014). Among such factors, we can mention cost reduction, service optimization, so as search for workforce capabilities or better technology (Winkler, 2009, p. 68).Modern economic and social studies encourage seeking for transdisciplinary insights derived from specialized disciplines, to aid various societies in finding solutions to contemporary problems. Managerial community involved in offshore operations is constantly struggling with various challenges and tries to find quick and successful solutions to reoccurring problems at different stages of organizational changes (Strielkowski and Weyskrabova, 2014; Kedziora et al., 2016). The core aim of this work is to provide review of selected legal issues identified as most challenging for service offshoring managerial community at pre-transition stage (during assessment and preparation for strategic decision of transferring services to a different EU country), in light of economic and social aspects. A need for strengthening this area of knowledge was identified from insights expressed by interviewees, emphasizing lack of such easily available study, presenting topic in a consistent and understandable way, not merely for law professionals. In this paper, following research questions shall be addressed:1. How can we identify and classify potential challenges that might present themselves before start of a service offshoring transition project?2. How can we present legal regulations important for business offshoring managerial community in a straightforward and cohesive way?3. What impact may these issues have on economies and societies of EU member states involved?1.Theoretical backgroundService offshoring should be understood as the transnational relocation or dispersion of service activities, previously performed by companies in their home country, including captive (internal) and outsourced (external) operational models (Doh et al. …