Lossless Transfer Research Articles

Stretchable superhydrophobic fluororubber fabricated by transferring mesh microstructures.

Stretchable flexible superhydrophobic surfaces are in great demand to achieve waterproofing performance in aerospace, electronic industry, and other fields. However, there are still many challenges in developing superhydrophobic surfaces, which maintain their wetting characteristics under high strain conditions with good tensile durability. Here, we propose a simple and efficient method to prepare a stretchable superhydrophobic fluororubber surface composed of hierarchical micro-convexities, which are orderly arranged and interconnected. Its peculiar structure shows excellent superhydrophobicity (155.48 ± 1.97°) and high water sliding angle due to Cassie's impregnating wetting regime. Due to the special structure and high mechanical strength of the surface, it can still maintain its superhydrophobic property after a variety of durability tests, including various stretching tests, sandpaper abrasion, sand impact, and high-temperature treatment. In addition, the surface can still realize the lossless transfer of water droplets even at large stretching strains, which is expected to be applied to microfluidic devices under extreme working conditions.

Design of a simple nanoscale hydrophilic-hydrophobic heterojunction system with under-liquid dual superlyophobicity for application in controllable droplet-based microreactor system and oil/water emulsions separation

Recently, many superwetting materials have emerged to deal with environmental problems. Among them, the under-liquid dual superlyophobic superwetting surface has attracted widespread attention due to the possessing of underwater superoleophobicity and underoil superhydrophobicity at the same time, and without the requirement of any energy stimulation when compared to conventional or responsive superwetting surfaces. However, A rational design of this deliciated surface state still lacking. Herein, a novel dual superlyophobic surface was achieved by simply modulating the relative proportion of a nanoscale hydrophilic-hydrophobic heterojunction system - cellulose nanofibrils (CNFs) and graphited multiwalled carbon nanotubes (gMWCNTs), and without any additional chemical modification. Besides, the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory or extended-DLVO (EDLVO) theory was introduced first to help understand the wettability variation of such a heterogeneous surface, which is mainly attributed to the changing stability of oil or water film covering the membrane surface. Additionally, this novel nanoscale hydrophilic-hydrophobic heterojunction system with dual superlyophobicity and excellent flexibility can not only separate both oil-in-water emulsion and water-in-oil emulsion simultaneously, but also achieve the lossless transfer in the droplet-based microreactor system under both water and oil environments. This may bring novel applications to the field of dual superlyophobicity. Moreover, this nanoscale hydrophilic-hydrophobic heterojunction system offers new and universal theoretical guidance for facile preparation of dual superlyophobic surfaces, owing to the richness in the functionality of low dimensional nanomaterials, it is foreseeable that more potential applications in various fields can be coupled with such an adaptable platform.

Molecular Laser Cooling in a Dynamically Tunable Repulsive Optical Trap.

Recent work with laser-cooled molecules in attractive optical traps has shown that the differential ac Stark shifts arising from the trap light itself can become problematic, limiting collisional shielding efficiencies, rotational coherence times, and laser-cooling temperatures. In this Letter, we explore trapping and laser cooling of CaF molecules in a ring-shaped repulsive optical trap. The observed dependences of loss rates on temperature and barrier height show characteristic behavior of repulsive traps and indicate strongly suppressed average ac Stark shifts. Within the trap, we find that Λ-enhanced gray molasses cooling is effective, producing similar minimum temperatures as those obtained in free space. By combining in-trap laser cooling with dynamical reshaping of the trap, we also present a method that allows highly efficient and rapid transfer from molecular magneto-optical traps into conventional attractive optical traps, which has been an outstanding challenge for experiments to date. Notably, our method could allow nearly lossless transfer over millisecond timescales.

Interlaced wetting surfaces with switchable wettability for manipulating underwater oil droplets

Biomimetic surfaces that can manipulate droplets have attracted intense attention because of their application prospects in the fields of drug detection, cell sorting, bio-sensor, etc. Although many promising advances have been made, it is still a challenge to achieve lossless, no cross-contamination and on-demand controllable manipulation of underwater oil droplets without external energy input. Herein, SHI & SLIP interlaced wetting smart surfaces were fabricated by a simple strategy for manipulating underwater oil droplets. Depending on the switchable wettability and reasonable alternating wetting, the lubricant-infused area and superhydrophilic area can be on-demand controlled on the same surface. Numerical calculation and theoretical analysis reveal that the energy barrier between different interfaces is an important factor to realize underwater oil droplet manipulation. By the rational design of the interlaced wetting pattern, the capture, lossless transfer, fusion and directional transportation of underwater oil droplets were realized. Besides, the as-prepared surface has cross-contamination resistance, stable wettability and rewritability, which expands the application field and improves the potential value. We expect this work to open new avenues for flexible and controllable manipulation of underwater oil droplets and promote the development of smart microfluidic platform. It is also expected to be used in unpowered delivery systems, micro-reactions and energy transfer.

Near Lossless Transfer Learning for Spiking Neural Networks

Spiking neural networks (SNNs) significantly reduce energy consumption by replacing weight multiplications with additions. This makes SNNs suitable for energy-constrained platforms. However, due to its discrete activation, training of SNNs remains a challenge. A popular approach is to first train an equivalent CNN using traditional backpropagation, and then transfer the weights to the intended SNN. Unfortunately, this often results in significant accuracy loss, especially in deeper networks. In this paper, we propose CQ training (Clamped and Quantized training), an SNN-compatible CNN training algorithm with clamp and quantization that achieves near-zero conversion accuracy loss. Essentially, CNN training in CQ training accounts for certain SNN characteristics. Using a 7 layer VGG-* and a 21 layer VGG-19, running on the CIFAR-10 dataset, we achieved 94.16% and 93.44% accuracy in the respective equivalent SNNs. It outperforms other existing comparable works that we know of. We also demonstrate the low-precision weight compatibility for the VGG-19 structure. Without retraining, an accuracy of 93.43% and 92.82% using quantized 9-bit and 8-bit weights, respectively, was achieved. The framework was developed in PyTorch and is publicly available.

Femtosecond laser-induced shape memory polymer micropillar with tunable wettability and reversible adhesion for underwater oil droplet lossless transfer

Shape memory polymers (SMPs) with tunable wettability and reversible adhesion through adjusting the surface morphology have great prospects in functional devices. However, current functional devices based on SMPs are mainly concentrated on the manipulation of diverse liquid droplets in the air; it is still a challenge to achieve the reversible tuning of underwater oil wettability and adhesion on the microstructured SMP surface. Herein, we fabricate a kind of SMP micropillar array through one-step femtosecond laser irradiation, which could achieve the reversible tuning of underwater oil wettability and adhesion between the tilted and upright states. It is worth noting that the deformed micropillar arrays show underwater oleophobicity and have a larger adhesion force to the oil droplet than that of upright micropillar arrays, which is mainly related to the variation of the contact area between the oil droplet and the micropillar array. Finally, we demonstrate the lossless oil droplet transfer underwater by using the micropillar array surface with different states. We believe the present work will bring some insights for researchers in the field of dynamically responsive tunable underwater oil droplet manipulation.

Kalman Filtering Based Adaptive Transfer in Energy Harvesting IoT Networks

In this paper, we investigate an energy prediction algorithm based on Kalman filtering in energy harvesting IoT networks. The IoT nodes harvest renewable energy from nature and powered by green energy only. Owing to the space-time instability and non-uniformity of renewable energy, the IoT nodes may have insufficient energy supply. An unresolved challenge is accurately predicting the available renewable energy, and developing low complexity solutions that incorporate a lossless transfer guarantee. With this in mind, we propose the energy prediction algorithm based on Kalman filtering to bridge the gap between lossless transfer and unstable renewable energy. The energy prediction is performed at the access point in order to dynamically adjust the number of bits to be sent, and the data loss due to receiver energy depletion will be improved. In addition, real solar and wind energy profiles are exploited by simulations. The simulation results show that the proposed energy prediction algorithm can improve transmission efficiency in terms of the rate of drop bits and the number of time slots needed to transmit a given payload, and reduce the wastes of harvested renewable energy.

Low Complexity Iterative Receiver With Lossless Information Transfer for Non-Binary LDPC Coded PDMA System

In this work, we first proposed a non-binary low-density parity-check (NB-LDPC) coded pattern division multiple access (PDMA) scheme with the order of the Galois field equal to the size of modulation alphabet which can avoid the symbol-to-bit or bit-to-symbol probability conversion between the detector and decoder as in binary coded system. Specifically, we considered a 4-ary LDPC over Galois field (GF(4)-LDPC) coded PDMA system with quadrature phase shift keying (QPSK) modulation. At the receiver side, Gaussian approximation based message passing (GAMP) detection algorithm instead of standard message passing (SMP) is employed to achieve a tradeoff between the computational complexity and the detection performance. When iterative detection and decoding (IDD) algorithm is used, the symbol-wise extrinsic information of the detector and GF(4)-LDPC decoder can be exchanged without information loss. At last, we proposed a symbol-wise EXIT (S-EXIT) based iterative optimization algorithm to improve the system performance. Both the S-EXIT chart based analysis and numerical simulation results show the validity of the proposed scheme above.

Data Compression mechanisms in an intelligent E-Health gateway for medical monitoring applications

Abstract In this article, we present data Compression mechanisms in an intelligent E-Health gateway for medical monitoring applications, to improve the collection and processing of data in the context of medical surveillance. These mechanisms, will not only optimize the data storage space required by the gateway, but also to accelerate the processing of the data flow for the fast and lossless transfer of data on the WSN (Wireless Sensor Network) and WLAN (Wireless Local Area Network) networks. In addition, all of the modern data compression mechanisms presented in this article are the following: Forecast compression, Sampling compression, Scheduling compression, distributed compression. We apply some formats of lossless data compression algorithms to these mechanisms (LZ4, LZO and Bzip2), to establish a comparative study between mechanisms using metric parameters. The implementation of these mechanisms in the smart gateway highlights an advanced Internet of Things data processing system for health and medical surveillance, based on a comprehensive and efficient study of advanced data compression techniques.

Reversible lossless manipulation of water droplets with large‐range volume

The lossless manipulation of microdroplets has great promising applications in the fields of such as liquids transportation. In recent years, superhydrophobic surfaces with low adhesion have been utilised as an effective solid surface to realise the lossless transfer of liquids. However, the present methods using superhydrophobic surfaces are hard to realise the reversible lossless manipulation of water droplets with a large-range volume. Here, a special transfer pipette composed of a superhydrophobic hole and an optimised pressure-generation device is developed to realise the lossless manipulation of water droplets. The superhydrophobic surfaces are obtained by electrochemical etching, boiling-water immersion and stearic acid modification, showing an excellent superhydrophobicity with a water contact angle of ~165° and roll-off angle of ~2°. The capture and release of water droplets are realised via controlling the resultant force of the vertical component of capillary force and gravity of droplets. The applied pressure is far less than the threshold pressure which guaranties the lossless property in the manipulation processes. The operable limiting volume of water droplets even reaches to 1404 μL, showing a large-range operable volume. Moreover, the strategy can easily realise the reversible and repeatable manipulation showing potential applications in the biological and microfluidic fields.

Research progress of high-quality monolayer MoS2 films

As an emerging two-dimensional (2D) material, monolayer molybdenum disulfide films show excellent electrical and optical properties and have aroused great interest due to their potential applications in electronics and optoelectronics. In this paper, we review our works about molybdenum disulfide films in the past few years. Chemical vapor deposition (CVD) is a convenient and low-cost method to synthesize 2D materials. By oxygen-assisted CVD, the wafer-scale highly-oriented monolayer molybdenum disulfide films and large single-crystal monolayer molybdenum disulfide on various substrates have been prepared epitaxially. Preparation of high-quality monolayer molybdenum disulfide films is the key to measure its intrinsic properties and realize its large-scale applications. Besides the preparation of high-quality materials, the optimizing of transfer technique and fabrication technique are of equal importance for improving the properties of electronic and optoelectronic devices. Water-assisted lossless transfer, patterned peeling, structural change and local phase transition of monolayer molybdenum disulfide films pave the way for preparing and optimizing the functionalized devices. For example, water-assisted transfer and patterned peeling provide methods of preparing molybdenum disulfide samples with clean surfaces and interfaces. Phase transition in the contact area of field-effect transistor reduces the contact resistance effectively, which improves the electrical performance. In addition, the heterojunctions of molybdenum disulfide and other 2D materials show novel electrical and optical properties. As for the functional devices, ultrashort-channel field-effect transistors, integrated flexible thin film transistors, and humidity sensor array have been realized with monolayer molybdenum disulfide films. A grain boundary widening technique is developed to fabricate graphene electrodes for ultrashort-channel monolayer molybdenum disulfide transistors. Field-effect transistors with channel lengths scaling down to 4 nm can be realized reliably and exhibit superior performances, such as the nearly Ohmic contacts and excellent immunity to short channel effects. Furthermore, monolayer molybdenum disulfide films show excellent electrical properties in the measurement of integrated flexible thin film transistors. Under a uniaxial stain of 1%, the performance of the device shows no obvious change, revealing not only the high quality of CVD-grown molybdenum disulfide films, but also the stabilities of these flexible thin film transistor devices. Molybdenum disulfide humidity sensor array for noncontact sensation also shows high sensitivity and stability. Mobility and on/off ratio of the devices in the array decrease linearly with the relative humidity increasing, leading to a high sensitivity of more than 104. The study of monolayer molybdenum disulfide films is universal and instructive for other 2D transition metal dichalcogenides.

Bioinspired platform with reversibly switchable wettability for transfer and storage of droplets

Inspired by rose petals, a novel and facile method to prepare smart surface with controllable wettability for transfer and patterned storage of droplets was presented. The smart surface was obtained by alternately depositing PDDA and PSS on a copper substrate with mastoid structure prepared by laser processing. It was found that the wettability of the as-prepared copper surface can switch reversibly between superhydrophobic and superhydrophilic state. In addition, the as-prepared surface had excellent physical and chemical stability. In theory, our droplet storage platform can be processed into any size and shape to achieve different requirements for droplet storage. This study provides a simple route to fabricate bioinspired rewritable platform with reversibly switchable wettability for lossless transfer and patterned storage of droplets. It may be helpful for the development of the devices for droplet transfer and functionalized droplet storage. This method can also be applied to biodetection, microfluidic switching, and chemical microreaction.

Behavioural digital modelling of lossy frequency‐periodic microwave passive filters

The theoretically synthesised power transmission response of several classes of RF/microwave passive filters is frequency periodic. Examples of these filters include those exploiting signal-interference techniques as well as those consisting of stub-loaded circuit networks. A behavioural z -plane digital modelling of these ideally synthesised frequency-periodic high-frequency filters has been recently proposed. It led to innovative explanations for commonly observed spurious resonant peaks and circuit redundancies in suboptimal designs. This work reports on a novel behavioural discrete-time modelling methodology for frequency-periodic microwave lossy filters. It considers for the first time the effect of high-frequency losses by introducing a σ parameter on the originally lossless transfer function. For practical-validation purposes, the manufacturing and characterisation of a new type of generalised stub-loaded-based extended-upper-stopband bandpass filter along with its lossy digital modelling are shown.

Positive-real systems under lossless transformations: Invariants and reduced order models

In this paper, positive-real systems under lossless positive-real transformations are investigated. Let G(s) be the transfer function matrix of a continuous-time positive-real system of order n and F(s) a lossless transfer function of order nF. We prove here that the lossless positive-real transformed system, i.e. G(F(s)), is also positive-real. Furthermore, the stochastic balanced representation of positive-real systems under lossless positive-real transformations is considered. In particular, it is proved that the positive-real characteristic values πj of G(F(s)) are the same of G(s) each with multiplicity nF, independently from the choice of F(s). This property is exploited in the design of reduced order models based on stochastic balancing. Finally, the proposed technique is a passivity preserving model order reduction method, since it is proven that the reduced order model of G(F(s)) is still positive-real. An error bound for truncation related to the invariants πj is also derived.

New Results and Techniques for Computation of Stored Energy in Lossless/All-Pass Systems

Lossless and all-pass systems are energy-conservative in the sense that the energy that is extracted from the system always equals that supplied to the system. This stored energy turns out to be independent of the system realization/description. For example, there are different LC realizations of a lossless transfer function, but the energy stored can be uniquely expressed in terms of the port variables and their derivatives. This paper proposes new results and algorithms to compute the stored energy in lossless systems. We present four different techniques to compute the stored energy of lossless/all-pass systems. The first method is LC realization based (Foster, Cauer and their combinations) and the second is based on the Bezoutian of two polynomials. The notion of “balancing controllability/observability Gramians” is used for the third, while the last method is based on adjoint networks. A comparative study among the four methods shows that the first three methods are comparable with respect to computation time, while for numerical accuracy, the Bezoutian method is the best. Three different methods to compute the Bezoutian is also reported here: Euclidean long division, Pseudo-inverse method and the two dimensional discrete Fourier transform.

Diffusive lossless energy and coherence transfer by noisy coupling

Here we show that noisy coupling can lead to diffusive lossless energy transfer between individual quantum systems retaining a quantum character leading to entangled stationary states. Coherence might flow diffusively while being summarily preserved even when energy exchange is absent. Diffusive dynamics persists even in the case when additional noise suppresses all the unitary excitation exchange: arbitrarily strong local dephasing, while destroying quantum correlations, is not affecting energy transfer.

Rapid Fabrication of T-Shaped Micropillars on Polypropylene Surfaces with Robust Cassie–Baxter State for Quantitative Droplet Collection

Applying microinjection compression molding technology, a fast and flexible method is first proposed for the successive and mass replication of polypropylene surfaces with T-shaped micropillars in the present work. The water droplet on the titled surfaces grows in size to roll off due to gravitation effect. Interestingly, the roll-off angles on such surfaces are as a quadratic function of specified water droplet volume, meaning quantitative droplet collection and lossless transfer can be performed on the replicated surfaces. Meanwhile, self-cleaning behavior is preserved on the surfaces. Moreover, the robust Cassie–Baxter state on the replicated surfaces against the external pressure is demonstrated with droplet compression and immersion experiments. Specifically, a droplet sitting on the replicated surface can recover its spherical shape after squeezed to a water film as thin as 0.37 mm, and the replica is remained fully spotless after it is submerged into dyed water. The proposed method for fast replica...

The welfare costs of rent-seeking: a methodologically individualist and subjectivist revision

Gordon Tullock is acknowledged for being the first to recognize the true costs of rent-seeking as including not only the Harberger triangle but also the Tullock rectangle. This rectangle does not constitute merely a lossless transfer of wealth, but it causes a misallocation of resources as rent-seekers invest resources in lobbying. However, a close reading of Tullock’s writings shows that his arguments are formulated in a holistic fashion, speaking of what is efficient or inefficient for society. Rent-seeking is inefficient because it reduces societal welfare. But according to a methodologically individualist and subjectivist economics, such a claim is invalid. We must distinguish between positive economic fact and normative moral philosophy. We call for a reconstruction of utility and welfare economics based on methodological individualism and subjectivism with implications for the theories of monopoly and competition: practices which Neoclassical perfect-competition theory considers to be evidence of rent-seeking should instead be deemed as indications of genuine competition Political economy should be concerned with ascertaining which institutions will best enable individuals to pursue their individually subjective ends – or else economists should be explicit about their normative preferences and political philosophies.

Flexible Transparent Hierarchical Nanomesh for Rose Petal‐Like Droplet Manipulation and Lossless Transfer

Precise manipulation of water is a key step in numerous natural and synthetic processes. Here, a new flexible and transparent hierarchical structure is determined that allows ultra‐dexterous manipulation and lossless transfer of water droplets. A 3D nanomesh is fabricated in one step by scalable electrospinning of low‐cost polystyrene solutions. Optimal structures are composed of a mesh of dense nanofiber layers vertically separated by isolated mesoporous microbeads. This results in a highly adhesive superhydrophobic wetting that perfectly mimics rose petal‐like structures. Structural–functional correlations are obtained over all key process parameters enabling robust tailoring of the wetting properties from hydrophilic to lotus‐like Cassie‐Baxter and rose‐like Cassie‐impregnating states. A mechanistic model of the droplet adhesion and release dynamics is obtained alongside the first demonstration of a mechanically induced transfer of microdroplets between two superhydrophobic coatings. This low‐temperature reaction‐free material structure demonstrates a facile means to fabricate impenetrable residue‐less rose petal‐like surfaces with superhydrophobic contact angles of 152 ± 2° and effective adhesion strength of 113 ± 20 μN. This is a significant step toward parallel, multistep droplet manipulation with applications ranging from flexible on‐paper devices to microfluidics and portable/wearable biosensors.

The Research of Equalizing Charge Control Strategy for Series Connected Power Battery

In order to meet the demand of power supply voltage and capacity, power battery usually uses multiple single cells in series. Due to that performance difference will be increased in the process of charging and discharging, eventually it leads to a sharp drop in battery performance and shorten the cycle life. By analyzing the causes of battery failure in advance, the design is based on the energy storage the inductance of the non dissipative equalization circuit. According to the different status of a single cell in the battery pack, the fuzzy control algorithm can fine-tuning the charging current of single battery through balanced circuit, so as to realize rapid equalization charging of the battery pack. This paper makes a comparison with the charging simulation experiment by using charging model of four batteries in series. Experimental results show that the imbalance between the battery pack can cause damage to the battery and cannot make each battery charged in. The designed balance circuit and fuzzy equilibrium controller designed can realize lossless transfer of energy to reduce the inconsistency of each single cell and achieve the requirement of the equalizing charge.