Experimental investigation on de-icing by an array of impact rod-type plasma synthetic jets

Since flight accidents due to aircraft icing occur from time to time,this paper proposes an array of impact rod-type plasma synthetic jet de-icing methods for aircraft icing problems.The impact rod-type plasma synthetic jet actuator(PSJA)is based on the traditional PSJA with an additional impact rod structure for better de-icing in the flight environment.In this work,we first optimize the ice-breaking performance of a single-impact rod-type PSJA,and then conduct an array of impact rod-type plasma synthetic jet ice-breaking experiments to investigate the relationship between crack expansion and discharge energy,ice thickness and group spacing.The results show that the impact force and impulse of a single-impact rod-type PSJA are proportional to the discharge energy,and there exists a threshold energy Qmin for a single actuator to break the ice,which is proportional to the ice thickness.Only when the discharge energy reaches above Qmin can the ice layer produce cracks,and at the same time,the maximum radial crack length produced during the ice-breaking process is proportional to the discharge energy.When the ice is broken by an array of impact rod PSJAs,the discharge energy and group spacing together determine whether the crack can be extended to the middle region of the actuator.When the group spacing is certain,increasing the energy can increase the intersection of cracks in the middle region,and the ice-fragmentation degree is increased and the ice-breaking effect is better.At the same time,the energy estimation method of ice breaking by an array of impact rod-type PSJAs is proposed according to the law when a single actuator is breaking ice.

State of the art and practice of pavement anti-icing and de-icing techniques

Pavement snow and icing are worldwide problems, but effective countermeasures are just beginning to be developed in China. The two most common snow and ice removal methods are mechanical clearance and chemical melting, and the advantages and disadvantages of each approach are discussed here, including environmental and structural damage caused by corrosive snow melting agents. New developments in chemical melting agents and mechanical equipment are discussed, and an overview of alternative thermal melting systems is presented, including the use of geothermy and non-geothermal heating systems utilizing solar energy, electricity, conductive pavement materials, and infrared/microwave applications. Strategic recommendations are made for continued enhancement of public safety in snow and ice conditions.

Peridynamic modeling and simulation of thermo-mechanical de-icing process with modified ice failure criterion

De-icing technology has become an increasingly important subject in numerous applications in recent years.However,the direct numerical modeling and simulation the physical process of thermomechanical deicing is limited.This work is focusing on developing a numerical model and tool to direct simulate the de-icing process in the framework of the coupled thermo-mechanical peridynamics theory.Here,we adopted the fully coupled thermo-mechanical bond-based peridynamics(TM-BB-PD)method for modeling and simulation of de-icing.Within the framework of TM-BB-PD,the ice constitutive model is established by considering the influence of the temperature difference between two material points,and a modified failure criteria is proposed,which takes into account temperature effect to predict the damage of quasi-brittle ice material.Moreover,thermal boundary condition is used to simulate the thermal load in the de-icing process.By comparing with the experimental results and the previous reported finite element modeling,our numerical model shows good agreement with the previous predictions.Based on the numerical results,we find that the developed method can not only predict crack initiation and propagation in the ice,but also predict the temperature distribution and heat conduction during the de-icing process.Furthermore,the influence of the temperature for the ice crack growth pattern is discussed accordingly.In conclusion,the coupled thermal-mechanical peridynamics formulation with modified failure criterion is capable of providing a modeling tool for engineering applications of de-icing technology.

Dose-effect correlation of chloride de-icing salt on Euonymus japonicus

In order to prevent severe pollution by de-icing salt on greenery along urban roads, a half lethal dose （LD_50）for a plant population was confirmed through stress simulation of chloride de-icing salt on Euonymus japonicus, with an ianalysis of physiological changes, statistics on mortality rate on plant populations and mathematic modeling during a 30- day subacute toxicity test. The results indicate that a significant positive correlation in the early stages and a significant negative correlation in the later stages were observed between the amount of chlorophyll a and b in plants and a cumulative dose of de-icing salt. The amounts of free proline in plants and the dose of de-icing salt were positively correlated Over the entire period. No significant correlation in the initial stage, but a significant negative correlation in later stages was observed between the soluble protein and the dose of de-icing salt. LDs0 of this chloride agent on E. japonicus is 5 kg.（L·m2）-1 over 30 days.

Self-Structured Organizing Single-Input CMAC Control for De-icing Robot Manipulator

This paper presents a self-structured organizing single-input control system based on differentiable cerebellar model articulation controller (CMAC) for an n-link robot manipulator to achieve the high-precision position tracking. In the proposed scheme, the single-input CMAC controller is solely used to control the plant, so the input space dimension of CMAC can be simplified and no conventional controller is needed. The structure of single-input CMAC will also be self-organized;that is, the layers of single-input CMAC will grow or prune systematically and their receptive functions can be automatically adjusted. The online tuning laws of single-input CMAC parameters are derived in gradient-descent learning method and the discrete-type Lyapunov function is applied to determine the learning rates of the proposed control system so that the stability of the system can be guaranteed. The simulation results of three-link De-icing robot manipulator are provided to verify the effectiveness of the proposed control methodology.

Photothermal superhydrophobic copper nanowire assemblies: fabrication and deicing/defrosting applications

Ice and frost buildup continuously pose significant challenges to multiple fields.As a promising de-icing/defrosting alternative,designing photothermal coatings that leverage on the abundant sunlight source on the earth to facilitate ice/frost melting has attracted tremendous attention recently.However,previous designs suffered from either localized surface heating owing to the limited thermal conductivity or unsatisfied meltwater removal rate due to strong water/substrate interaction.Herein,we developed a facile approach to fabricate surfaces that combine photothermal,heat-conducting,and superhydrophobic properties into one to achieve efficient de-icing and defrosting.Featuring copper nanowire assemblies,such surfaces were fabricated via the simple template-assisted electrodeposition method,allowing us to tune the nanowire assembly geometry by adjusting the template dimensions and electrodeposition time.The highly ordered copper nanowire assemblies facilitated efficient sunlight absorption and lateral heat spreading,resulting in a fast overall temperature rise to enable the thawing of ice and frost.Further promoted by the excellent water repellency of the surface,the thawed ice and frost could be spontaneously and promptly removed.In this way,the all-in-one design enabled highly enhanced de-icing and defrosting performance compared to other nanostructured surfaces merely with superhydrophobicity,photothermal effect,or the combination of both.In particular,the defrosting efficiency could approach∼100%,which was the highest compared to previous studies.Overall,our approach demonstrates a promising path toward designing highly effective artificial deicing/defrosting surfaces.

Piezoelectric resonant ice protection systems–Part1/2:Prediction of power requirement for de-icing a NACA 0024 leading edge

This paper proposes a numerical method to analyze the ice protection capability and predict the power requirements of a piezoelectric resonant de-icing system.The method is based on a coupled electro-mechanical finite element analysis which enables the fast computation of the modes of resonance of interest to de-ice curved surfaces and the estimation of the input voltage and current required for a given configuration(defined by its mode,actuator location,ice deposit,etc.).Eventually,the electric power to be supplied can be also assessed.The method is applied to a NACA 0024 leading edge equipped with piezoelectric actuators.First,two extension modes are analyzed and compared with respect to their efficiency and power requirements.Then,tests are carried out in an icing tunnel to verify the effectiveness of the piezoelectric ice protection system and the predictions of the maximal required power.The system allows de-icing the leading edge in less than 2 s for a glaze ice deposit.

DC Traction Power Supply System Based on Modular Multilevel Converter Suitable for Energy Feeding and De-icing

A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.

PREDICTION OF RIME ICE ACCRETION AND RESULTING EFFECT ON AIRFOIL PERFORMANCE

The roughness effect based on the wall function method is introduced into the numerical simulation of the rime ice accretion and the resulting effect on the aerodynamic performance of the airfoil. Incorporating the two-phase model of air/super-cooled droplets in the Eulerian coordinate system, this paper presents the simulation of the rime ice accretion on the NACA 0012 airfoil. The predicted rime ice shape is compared with those results of measurements and simulations by other icing codes. Also the resulting effects of rime ice on airfoil aerodynamic performance are discussed. Results indicate that the rime ice accretion leads to the loss of the maximum lift coefficient by 26%, the decrease of the stall angle by about 3° and the considerable increase of the drag coefficient.

Review:On dendritic cell-based therapy for cancers

Dendritic cells (DCs), the most prevalent antigen-presenting cell in vivo, had been widely characterized in the last three decades. DCs are present in almost all tissues of the body and play cardinal roles in recognition of microbial agents,autoantigens, allergens and alloantigen. DCs process the microbial agents or their antigens and migrate to lymphoid tissues to present the antigenic peptide to lymphocytes. This leads to activation of antigen-specific lymphocytes. Initially, it was assumed that DCs are principally involved in the induction and maintenance of adaptive immune responses, but now it is evident that DCs also have important roles in innate immunity. These features make DCs very good candidates for therapy against various pathological conditions including malignancies. Initially, DC-based therapy was used in animal models of cancers. Data from these studies inspired considerable optimism and DC-based therapies was started in human cancers 8 years ago. In general,DC-based therapy has been found to be safe in patients with cancers, although few controlled trials have been conducted in this regard. Because the fundamentals principles of human cancers and animal models of cancers are different, the therapeutic efficacy of the ongoing regime of DC-based therapy in cancer patients is not satisfactory. In this review, we covered the various aspects that should be considered for developing better regime of DC-based therapy for human cancers.

Design of an Experimental Set‑up Concerning Interfacial Stress to Promote Measurement Accuracy of Adhesive Shear Strength Between Ice and Substrate

Accumulation of ice on airfoils and engines seriously endangers the safety of the fight.The accurate measurement of adhesion strength at the ice-substrate interface plays a vital role in the design of anti/de-icing systems.In this pursuit,the present study envisages the evaluation of the stress at the icesubstrate interface to guide the design of experimental set-ups and improve the measurement accuracy of shear strength using the finite element analysis(FEA)method.By considering such factors as the peeling stress,maximum von-mises stress and uniformity of stress,the height and radius of ice and the loading height are investigated.Based on the simulation results,appropriate parameters are selected for the experimental validation.Simulation results show that the peeling stress is decreased by reducing the loading height and increasing the height of ice.Higher ice,increasing loading height and smaller ice radius are found to be beneficial for the uniformity of stress.To avoid cracks or ice-breaking,it is imperative that the ice should be of a small radius and greater height.Parameters including the ice height of 25 mm,radius of 20 mm,and loading height of 9 mm are adopted in the experiment.The results of FEA and the experimental validation can significantly enhance the measurement accuracy of shear strength.

Optimized and coordinated model predictive control scheme for DFIGs with DC-based converter system

This paper proposes an optimized and coordinated model predictive control(MPC) scheme for doublyfed induction generators(DFIGs) with DC-based converter system to improve the efficiency and dynamic performance in DC grids. In this configuration, the stator and rotor of the DFIG are connected to the DC bus via voltage source converters, namely, a rotor side converter(RSC) and a stator side converter(SSC). Optimized trajectories for rotorflux and stator current are proposed to minimize Joule losses of the DFIG, which is particularly advantageous at low and moderate torque. The coordinated MPC scheme is applied to overcome the weaknesses of the field-oriented control technique in the rotor flux-oriented frame, which makes the rotor flux stable and the stator current track its reference closely and quickly. Lastly, simulations and experiments are carried out to validate the feasibility of the control scheme and to analyze the steady-state and dynamic performance of the DFIG.

Design and Development of Anti-Icing Aluminum Surface

An anti-icing surface has been designed and prepared with an aluminum panel by creating an artificial lotus leaf which is highly hydrophobic. The hydrophobicity of a solid surface can be generated by decreasing its surface tension and increasing the roughness of the surface. On a highly hydrophobic surface, water has a high contact angle and it can easily rolls off, carrying surface dirt and debris with it. Super-cooled water or freezing rain can also run off this highly hydrophobic surface instead of forming ice on the surface, due to the reduction of the liquid-solid adhesion. This property can also help a surface to get rid of the ice after the water becomes frozen. In this study, a Cassie-Baxter rough surface was modeled, and an aluminum panel was physically and chemically modified based on the modeled structure. Good agreement was found between predicted values and experimental results for the contact and roll-off angles of water. Most importantly, by creating this highly hydrophobic aluminum rough surface, the anti-icing and de-icing properties of the modified surface were drastically improved compared to the control aluminum surface, and the cost will be reduced.

Evaluating the environmental impact of selected chemical de-icers

In this study,the environmental impacts of six commercial chloride-based de-icer products,including Rock Salt and Salt Brine,were evaluated.The nutrients,oxygen demand,heavy metal concentration,corrosion and toxicity of all six de-icers were analysed.With an assumed 500-fold dilution,the test results were compared to the public water-quality criteria.The results show that the selected chemical de-icers have little chance of severely damaging the environment and ecosystem under a normal dilution scenario.However,attention needs to be paid to small water bodies and sensitive receiving water.

A Review on Self-Cleaning Coatings for Tunnels

Self-cleaning coatings for tunnels can effectively remove dust and stains accumulated over the surface of tunnel linings and their appurtenances due to the closed environment and poor ventilation.This paper systematically introduces the current research status of self-cleaning coatings for tunnels,focusing on the development of super-hydrophobic self-cleaning coatings,superamphiphobic self-cleaning coatings,exhaust gas degradation coatings,fire retardant coatings,and tunnel de-icing coatings.The advantages and disadvantages of the five functional coatings are then briefly described,and the problems of self-cleaning coatings for tunnels at the present stage are pointed out.Finally,the development direction of self-cleaning coatings for tunnels is proposed to provide a reference for the research and application of self-cleaning coatings for tunnels.

Piezoelectric resonant ice protection systems-Part 2/2:Evaluation of benefits at aircraft level

Piezoelectric resonant de-icing systems are attracting great interest.This paper aims to assess the implementation of these systems at the aircraft level.The article begins with the model to compute the power requirement of a piezoelectric resonant de-icing system sized from the prototype detailed in Part 1/2 of this article.Then the mass,drag,and fuel consumption of this system and the subcomponents needed for its implementation are assessed.The features of a piezoelectric resonant de-icing system are finally computed for aircraft similar to Airbus A320 aircraft and aircraft of different categories(Boeing 787,ATR 72 and TBM 900)and compared with the existing thermal and mechanical ice protection systems.A sensitivity analysis of the main key sizing parameters of the piezoelectric de-icing system is also performed to identify the main axes of improvement for this technology.The study shows the potential of such ice protection systems.In particular,for the realistic input parameters chosen in this work,the electro-mechanical solution can provide a 54% reduction in terms of mass and a 92% reduction in terms of power consumption for an A320 aircraft architecture,leading to a 74% decrease in the associated fuel consumption compared to the actual air bleed system.

STING-activating dendritic cell-targeted nanovaccines that evoke potent antigen cross-presentation for cancer immunotherapy

Recently,nanovaccine-based immunotherapy has been robustly investigated due to its potential in governing the immune response and generating long-term protective immunity.However,the presentation of a tumor peptide-major histocompatibility complex to T lymphocytes is still a challenge that needs to be addressed for eliciting potent antitumor immunity.Type 1 conventional dendritic cell(cDC1)subset is of particular interest due to its pivotal contribution in the cross-presentation of exogenous antigens to CD8+T cells.Here,the DC-derived nanovaccine(denoted as Si9GM)selectively targets cDC1s with marginal loss of premature antigen release for effective stimulator of interferon genes(STING)-mediated antigen cross-presentation.Bone marrow dendritic cell(BMDC)-derived membranes,conjugated to cDC1-specific antibody(αCLEC9A)and binding to tumor peptide(OVA257-264),are coated onto dendrimer-like polyethylenimine(PEI)-grafted silica nanoparticles.Distinct molecular weight-cargos(αCLEC9A-OVA257-264 conjugates and 2′3′-cGAMP STING agonists)are loaded in hierarchical center-radial pores that enables lysosome escape for potent antigen-cross presentation and activates interferon type I,respectively.Impressively,Si9GM vaccination leads to the upregulation of cytotoxic T cells,a reduction in tumor regulatory T cells(Tregs),M1/M2 macrophage polarization,and immune response that synergizes with αPD-1 immune checkpoint blockade.This nanovaccine fulfills a dual role for both direct T cell activation as an artificial antigen-presenting cell and DC subset maturation,indicating its utility in clinical therapy and precision medicine.

Laboratory study of a hydronic concrete deck heated externally in a controlled sub-freezing environment

Geothermal heating of bridge decks is a reliable and sustainable method for bridge de-icing that has been in-creasing in demand since conventional de-icing methods were proved to be environmentally hazardous.Previous research on geothermal heating of bridge decks relied on hydronic pipes embedded inside of bridge decks,which are confined to newly constructed bridges.For existing bridges,a newly devised method for external heating has been recently tested under limited laboratory conditions to determine its overall performance.This study explores laboratory heating tests of a concrete slab with a thickness representing a typical concrete bridge deck.This slab was equipped with a simulated geothermal bridge de-icing system and tested inside a freezer subjected to sub-freezing controlled conditions.Various winter scenarios were applied to the system to determine its heat-ing performance and how feasible it will be for the system to be transferred to the field.A prediction equation was developed to estimate the total energy reserves required to permit de-icing,and statistical analysis was performed and validated with test results.The slab surface heat flux was estimated to range from 27 W/m^(2) K to 73 W/m^(2) K from the heating test.The externally-heated deck can be designed with the developed prediction equation for snow melting.

Impacts of de-icing salt pollution on urban road greenspace： a case study of Beijing

De-icing salt contamination of urban soil and greenspace has been a common issue of concern in many countries for years. In the 2009/2010 winter, Beijing experienced a contamination accident resulting from the overuse of deicing salt, reported as almost 30000 tons, which severely damaged urban vegetation alongside roadways. The methods of sampling and rating for both soil contamination and response of the plant populations were developed to rapidly assess this emergency environmental event. Results showed that the shrubs were more severely damaged than the arbors in terms of both degree and extent, as almost all of the surveyed shrubs were severely damaged from the salt contamination, while only about 1/4 of the recorded arbors were rated as ＂severely injured＂ according to the integral plant injury index. The rating of the injury level showed that the trees like Pinus bungeana, Sophora japonica, and the shrubs like Euonymus japonicus, Sabina vulgaris showed less tolerance to de-icing salt pollution. The patterns of vegetation damage demonstrated that the ever-green shrubs alongside roads and the deciduous arbors in the center of roads were most vulnerable to the salt damage.

Research progress on construction strategy and technical evaluation of aircraft icing accretion protection system

The impact of unstable supercooled water droplets suspended in the cloud on the solid will cause its surface to freeze,and the flight safety of the aircraft will be seriously affected when flying in this environment.Aircraft icing protection system is an important device to reduce icing accidents and improve aircraft safety performance,which is of great significance to ensure flight safety.Based on the energy source,this paper proposes a general strategy for constructing an aircraft icing protection system,including Active Anti-icing and De-icing(AAD)system,Passive Antiicing and De-icing(PAD)system and Composite Anti-icing and De-icing(CAD)system.The principle,scope of application,advantages and disadvantages of aircraft anti-icing and de-icing technologies such as electric pulse de-icing,low-frequency piezoelectric de-icing,and hydrophobic material anti-icing are explored in detail,and the corresponding improvement measures are proposed.The future development of aircraft anti-icing and de-icing technology is prospected,and some new ideas are provided for the improvement of aircraft anti-icing and de-icing technology.