Characterization of Asymmetric Tapered Dipole Nanoantenna for Energy Harvesting Applications

In this paper, systematic study for asymmetric tapered dipole nanoantenna is implemented using finite element frequency domain (FEFD) solver where harvesting efficiency, field confinement, surface current, and input impedance are calculated at wavelength of 500 nm. The proposed nanoantennas achieve a harvesting efficiency of 61.3% and a field enhancement factor of 37.7 over the conventional dipole nanoantenna. This enhancement is attributed to the irregularity of the surface current distribution on the asymmetric designs. Particle swarm optimization technique is used to find the optimum design geometrical parameters through an external link between the optimization algorithm and the FEFD solver. Moreover, the proposed designs offer a resonance impedance of 500 Ω to match that of fabricated rectifiers. Further study of the structure fabrication tolerance is included which shows the robustness of the proposed nanoantennas.     

Multiband Metamaterial Absorber Design Based on Plasmonic Resonances for Solar Energy Harvesting

A new metamaterial absorber is designed and characterized numerically for the harvesting of solar energy. The design is composed of three layers in which the interaction among them gives rise to the plasmonic resonances. The main operation frequency range of the proposed structure is chosen to be the visible regime. However, the design is also analyzed for the infrared and ultraviolet regimes. In order to characterize the absorber, some parametric studies with respect to the dimensions of the structure are carried out. According to the results, it is found that the proposed metamaterial absorber has 98.2 % absorption capability at 445.85 THz and 99.4 % absorption capability between 624 and 658.3 THz. Moreover, the polarization dependency of the structure is examined and it is found that the design operates well as a perfect absorber with polarization independency for the studied frequency range. As a result, the proposed metamaterial absorber can be used for solar energy harvesting as it provides multiple perfect absorption bands in the visible regime.     

Broadband Vibrational Energy Harvesting Based on a Triboelectric Nanogenerator

Vibrations in living environments are generally distributed over a wide frequency spectrum and exhibit multiple motion directions over time, which renders most of the current vibration energy harvesters unpractical for their harvesting purposes. Here, a 3D triboelectric nanogenerator (3D‐TENG) is designed based on the coupling of the triboelectrification effect and the electrostatic induction effect. The 3D‐TENG operates in a hybridization mode of conjuntioning the vertical contact‐separation mode and the in‐plane sliding mode. The innovative design facilitates harvesting random vibrational energy in multiple directions over a wide bandwidth. An analytical model is established to investigate the mechano‐triboelectric transduction of 3D‐TENG and the results agree well with experimental data. The 3D‐TENG is able to harvest ambient vibrations with an extremely wide working bandwidth. Maximum power densities of 1.35 W m^‐2 and 1.45 W m^‐2 are achieved under out‐of‐plane and in‐plane excitation, respectively. The 3D TENG is designed for harvesting ambient vibration energy, especially at low frequencies, under a range of conditions in daily life and has potential applications in environmental/infrastructure monitoring and charging portable electronics.     

Design and Analysis of Ultra Broadband Nano-absorber for Solar Energy Harvesting

In this paper, we propose a metamaterial based ultra broadband nano-absorber (UBNA) for solar energy harvesting, whose elements consist of a ring column and dual hexagon pillar at the center. In this absorber, the light of shorter wavelengths is harvested at ring column, while the light of longer wavelengths is trapped by dual hexagon pillar. It is found that the average absorptivity of the UBNA is as high as 96% in 300–1300 nm waveband and the UBNA can maintain 95% in the whole visible and near-infrared waveband ranging from 300 to 2000 nm. In addition, the perfect light absorbing capability of the UBNA is independent of the incident light polarization state in the waveband of 300–1300 nm, and it can keep up an average absorptivity of 91% with an large incident angle varying between ?60^° and 60^°. We attribute the perfect absorbing property of UBNA to the synergistic effect of the slow wave effect, Fabry-Perot resonance and the localized surface plasmon resonance enhancement.     

Graphene Based Materials: Enhancing Solar Energy Harvesting

Due to excellent electronic and optical properties as well as tunable work functions, graphene and graphene‐based materials are highly attractive for applications in enhancement of harvesting solar energy. In particular, they can be used as electron and hole transport materials, buffer layers, and window or/and counter electrodes in solar cells. This research news surveys very recent advances in this emerging field, with emphasis on fundamental understanding of their performance enhancement mechanisms for photovoltaic devices, and discusses future challenges.     

Broad Tunable Nanoantenna Based on Graphene Log-Periodic Toothed Structure

A log-periodic toothed nanoantenna based on graphene is proposed, and its multi-resonance properties with respect to the variations of the chemical potential are investigated. The field enhancement and radar cross-section of the antenna for different chemical potentials are calculated, and the effect of the chemical potential on the resonance frequency is analyzed. In addition, the dependence of the resonance frequency on the substrate is also discussed. It is shown that large modulation of resonance intensity in log-periodic toothed nanoantenna can be achieved via turning the chemical potential of graphene. The tunability of the resonant frequencies of the antenna can be used to broad tuning of spectral features. The property of tunable multi-resonant field enhancement has great prospect in the field of graphene-based broadband nanoantenna, which can be applied in non-linear spectroscopy, optical sensor, and near-field optical microscopy.     

GaSb‐Based Solar Cells for Full Solar Spectrum Energy Harvesting

In this work, a multijunction solar cell is developed on a GaSb substrate that can efficiently convert the long‐wavelength photons typically lost in a multijunction solar cell into electricity. A combination of modeling and experimental device development is used to optimize the performance of a dual junction GaSb/InGaAsSb concentrator solar cell. Using transfer printing, a commercially available GaAs‐based triple junction cell is stacked mechanically with the GaSb‐based materials to create a four‐terminal, five junction cell with a spectral response range covering the region containing >99% of the available direct‐beam power from the Sun reaching the surface of the Earth. The cell is assembled in a mini‐module with a geometric concentration ratio of 744 suns on a two‐axis tracking system and demonstrated a combined module efficiency of 41.2%, measured outdoors in Durham, NC. Taking into account the measured transmission of the optics gives an implied cell efficiency of 44.5%.     

用神经网络和遗传算法优化怀槐悬浮细胞合成异黄酮

为了获得怀槐悬浮细胞合成异黄酮的最适培养条件 ,采用ANNs(人工神经网络 )结合RAGA(实数编码加速遗传算法 )对培养基组成进行全局寻优。培养基中影响异黄酮染料木素产率的主要组成是KNO3、(NH₄)₂SO₄ 、2 ,4 D和 6 BA。在它们的有效作用浓度范围内 ,用随机10组培养基组合及细胞染料木素产率为输入和输出由ANNs对数据建模 ,由RAGA优化模型参数。建立的优化模型准确性高 ,依赖模型由RAGA全局寻优获得的最佳培养基组合是149.68mg L (NH₄)₂SO₄ 、2.936 1.0mg LKNO3、0.01mg L 2 ,4 D和 0.19mg L6-BA ,染料木素产率达14.13mg L ,与模型预测值的误差为 7.38%。结果表明 ,运用神经网络结合遗传算法优化怀槐细胞合成异黄酮的培养条件是可行的 ,优化后的培养基使怀槐细胞异黄酮合成能力比优化前有很大的提高.     

Skutterudite Unicouple Characterization for Energy Harvesting Applications

Skutterudites are promising thermoelectric materials because of their high figure of merit, ZT, and good thermomechanical properties. This work reports the effective figure of merit, ZT_eff, and the efficiency of skutterudite legs and a unicouple working under a large temperature difference. The p‐ and n‐type legs are fabricated with electrodes sintered directly to the skutterudite during a hot pressing process. CoSi₂ is used as the electrode for the n‐type skutterudite (Yb_0.35Co₄Sb₁₂) and Co₂Si for the p‐type skutterudite (NdFe_3.5Co_0.5Sb₁₂). A technique is developed to measure the ZT_eff of individual legs and the efficiency of a unicouple. An ZT_eff of 0.74 is determined for the n‐type legs operating between 52 and 595 °C, and an ZT_eff of 0.51 for the p‐type legs operating between 77 and 600 °C. The efficiency of the p–n unicouple is determined to be 9.1% operating between ～70 and 550 °C.     

Metamaterial-Based Energy Harvesting for Detectivity Enhanced Infrared Detectors

Plasmonics - In this paper, we propose new detectivity enhanced infrared detectors in which metamaterial cells are used to harvest the IR energy. Analytical models are developed and numerically...     

Energy Harvesting Technologies for Tire Pressure Monitoring Systems

Tire pressure monitoring systems (TPMS) are becoming increasingly important to ensure safe and efficient use of tires in the automotive sector. A typical TPMS system consists of a battery powered wireless sensor, as part of the tire, and a remote receiver to collect sensor data, such as pressure and temperature. In order to provide a maintenance‐free and battery‐less sensor solution there is growing interest in using energy harvesting technologies to provide power for TPMS. This paper summarizes the current literature and discusses the use of piezoelectric, electromagnetic, electret and triboelectric materials in a variety of harvesting systems.     

Robust Thin Films‐Based Triboelectric Nanogenerator Arrays for Harvesting Bidirectional Wind Energy

Wind‐driven triboelectric nanogenerators (TENGs) play an important role in harvesting energy from ambient environments. Compared to single‐side‐fixed triboelectric nanogenerator (STENG) arrays for harvesting single‐pathway wind energy, double‐side‐fixed triboelectric nanogenerator (DTENG) arrays are developed to harvest bidirectional wind energy. Electrical performances of the STENG and DTENG can be improved due to sticky, abrasive, and electrical properties of the Ti buffer layers among Al, polytetrafluoroethylene (PTFE), and polyimide (Kapton), configuring in triboelectric PTFE/Ti/Al and Al/Ti/Kapton/Ti/Al thin films. Short‐circuit current (I _SC), open‐circuit voltage (V _OC), and frequencies of the STENG and DTENG increase with increasing wind velocity ranging from 9.2 to 18.4 m s²¹, revealing that the moderate I _SC, V _OC, frequencies, and output powers of the STENG and DTENG reach 67 μA, 57 μA, 334 V, 296 V, 173 Hz, 162 Hz, 5.5 mW and 3.4 mW with a matched load of 4 MΩ at airflow rate of 15.9 m s²¹, respectively. Compared with counterparts of the single‐pathway‐harvested STENG arrays, the I _SC, durability, and stability of the bidirectional‐harvested DTENG can be dramatically improved by a 4 3 1 array connected in parallel because of the improved device configuration, stickiness, and abrasion by adhering Ti buffer layers. The durable DTENG arrays present a step toward practical applications in harvesting bidirectional wind energy for self‐powered systems and wireless sensors.     

基于混沌优化算法的MUSIC脑磁图源定位方法

如何利用实验测得的脑磁图数据准确定位脑磁图源的真实活动位置是脑功能研究和临床应用中的一个关键问题.在脑磁活动源定位问题中,多信号分类算法是被广泛研究和采用的一类方法.为了克服多信号分类算法及其改进算法--递归多信号分类算法全局扫描时速度太慢的缺点,提出了一种基于混沌优化算法的脑磁图源定位新方法.该方法利用混沌运动遍历性的特点估计目标函数的全局最大值,进行初步的脑磁图源定位;然后,在小范围内结合网格的方法,进一步进行精确的定位.实验结果表明,此方法可实现多个脑磁图源的定位,并且定位速度大大加快,同时又能达到所要求的定位精度.     

Improved Lower Bounds of DNA Tags Based on a Modified Genetic Algorithm

The well-known massively parallel sequencing method is efficient and it can obtain sequence data from multiple individual samples. In order to ensure that sequencing, replication, and oligonucleotide synthesis errors do not result in tags (or barcodes) that are unrecoverable or confused, the tag sequences should be abundant and sufficiently different. Recently, many design methods have been proposed for correcting errors in data using error-correcting codes. The existing tag sets contain small tag sequences, so we used a modified genetic algorithm to improve the lower bound of the tag sets in this study. Compared with previous research, our algorithm is effective for designing sets of DNA tags. Moreover, the GC content determined by existing methods includes an imprecise range. Thus, we improved the GC content determination method to obtain tag sets that control the GC content in a more precise range. Finally, previous studies have only considered perfect self-complementarity. Thus, we considered the crossover between different tags and introduced an improved constraint into the design of tag sets.     

Research on Laser Marking Speed Optimization by Using Genetic Algorithm

Laser Marking Machine is the most common coding equipment on product packaging lines. However, the speed of laser marking has become a bottleneck of production. In order to remove this bottleneck, a new method based on a genetic algorithm is designed. On the basis of this algorithm, a controller was designed and simulations and experiments were performed. The results show that using this algorithm could effectively improve laser marking efficiency by 25%.     

Wearable All‐Fabric‐Based Triboelectric Generator for Water Energy Harvesting

Realizing energy harvesting from water flow using triboelectric generators (TEGs) based on our daily wearable fabric or textile has practical significance. Challenges remain on methods to fabricate conformable TEGs that can be easily incorporated into waterproof textile, or directly harvest energy from water using hydrophobic textile. Herein, a wearable all‐fabric‐based TEG for water energy harvesting, with additional self‐cleaning and antifouling properties is reported for the first time. Hydrophobic cellulose oleoyl ester nanoparticles (HCOENPs) are prepared from microcrystalline cellulose, as a low‐cost and nontoxic coating material to achieve superhydrophobic coating on fabrics, including cotton, silk, flax, polyethylene terephthalate (PET), polyamide (nylon), and polyurethane. The resultant PET fabric‐based water‐TEG can generate an instantaneous output power density of 0.14 W m^?2 at a load resistance of 100 MΩ. An all‐fabric‐based dual‐mode TEG is further realized to harvest both the electrostatic energy and mechanical energy of water, achieving the maximum instantaneous output power density of 0.30 W m^?2. The HCOENPs‐coated fabric provides excellent breathability, washability, and environmentally friendly fabric‐based TEGs, making it a promising wearable self‐powered system.     

研究报告: 基于遗传算法的计算机辅助策略优化孕酮适配体

目的 本研究致力于优化孕酮（progesterone,P4）适配体的亲和力和选择性。方法 基于遗传算法（genetic algorithm,GA）的计算机辅助优化策略（in silico maturation,ISM）,进行了4轮GA操作（含交叉变异、单点突变和双点突变操作）,构建了初始文库和G1、G2、G3代ssDNA作为新的候选适配体库,采用分子对接对候选适配体进行筛选和分析,并使用迭代策略不断优化适配体。此外,还提出了一种较为准确预测ssDNA三级结构的方法,首先使用Mfold预测二级结构,继而使用RNAComposer建立与ssDNA相对应的RNA三级结构,输出的PDB文件使用Discovery Studio将RNA修改为DNA,最后使用Molecular Operating Environment对结构进行能量最小化处理。结果 到G2代,在局部搜索空间对P4S-0进行优化,筛选出P4G1-14、P4G2-20、P4G1-6、P4G1-7和P4G2-14这5条适配体作为P4的最佳候选适配体。采用AuNPs比色法初步验证优化后适配体的亲和力,继而构建了基于适配体结构开关的荧光法测定适配体的解离常数（equilibrium dissociation constant,K_D）,并以此方法对适配体的选择性（对双酚A、雌二醇、睾酮和皮质醇）进行了评估。结论 通过ISM优化后的适配体,对P4的亲和力较原适配体有了较大提升,仍保留着识别结构类似分子的选择性。     

Perspective Texture Synthesis Based on Improved Energy Optimization

Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it’s time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA) technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods.     

A Highly-Flexible and Breathable Photo-Thermo-Electric Membrane for Energy Harvesting

Photo-thermo-electric (PTE) technology is a simple but sustainable method that directly converts solar energy into electricity. However, the manufacturing of flexible and breathable PTE generators for practical applications, such as intelligent wearable and self-powered sensors, poses significant challenges due to the rigid thermoelectric materials and unbreathable substrates. Here, a highly-flexible and breathable photo-thermal-electric membrane (FB-PTEM) is developed by magnetron sputtering (MS) on a photo-thermal nanofiber membrane. A single unit of FB-PTEM produced an open-circuit voltage of 0.52 V under 1 sun (100 mW cm⁻²) and 0.2 V under LED illumination, making it suitable for all-weather use. The photo-thermal nanofiber membrane exhibited high photo-thermal conversion capacity of reaching 70 °C within 50 s under 1 sun irradiation. The FB-PTEM with a thickness of 0.35 mm achieved a self-temperature difference of 20.6 °C under 1 sun with the low thermal conductivity of the nanofiber membrane. Furthermore, it has a vapor permeability of 14.6 kg m⁻² d⁻¹ due to the inherent high porosity of the nanofiber membranes. The FB-PTEM demonstrates great potential for the development of highly flexible thermoelectric materials, as it encompasses various advantageous features such as self-temperature difference, lightweight design, high breathability, and all-weather suitability.