Lift Mode Research Articles

A new perspective on the aerodynamic performance and power limit of crosswind kite systems

In this paper, a new perspective on the aerodynamic performance modelling of crosswind kite power systems (CKPSs) is provided, where the effects of the induction factor or flow retardation by the kite are taken into account. For simplicity, only CKPSs in straight downwind configuration are considered, where the kites sweep an area perpendicular to the wind direction. Moreover, the in-plane or tangential induction factor is neglected. It is argued that the concept of the swept-area-normalized power coefficient, which is commonly used for conventional wind turbines, is not practically important for CKPSs. Instead, a kite-area-normalized power coefficient concept is adopted and is shown to be a more appropriate metric of performance of kite systems. The kite-area-normalized useful and wasted power coefficients for both a lift and a drag mode CKPS are plotted at different values of solidity factor and aerodynamic efficiency. Moreover, it is shown that the two modes of power generation, i.e. lift and drag modes, yield the same amount of useful power when the kite system solidity factor is essentially zero – this is in agreement with the underlying assumption in the crosswind kite power principle. For non-zero solidity factors, thus non-zero induction factors, however, our results suggest that the drag mode has higher power generation potential than the lift mode.

Risk of excavators overturning

PurposeTracked hydraulic excavators are versatile and ubiquitous items of off-highway plant and machinery that are utilised throughout the construction industry. Each year, a significant number of excavators overturn whilst conducting a lifting operation, causing damage to property, personnel injury or even fatality. The reasons for the overturn are myriad, including: operational or environmental conditions; machine operator acts or omissions; and/or inadequate site supervision. Furthermore, the safe working load (SWL) figure obtained from manufacturer guidance and utilised in lift plans is based upon undertaking a static load only. The purpose of this paper is to determine whether the SWL is still safe to be used in a lift plan when slewing a freely suspended (dynamic) load, and, if not, whether this may be a further contributory factor to overturn incidents.Design/methodology/approachPrevious research has developed a number of machine stability test regimes but these were largely subjective, impractical to replicate and failed to accurately measure the “dynamic” horizontal centrifugal force resulting from slewing the load. This research contributes towards resolving the stability problem by critically evaluating existing governing standards and legislation, investigating case studies of excavator overturn and simulating the dynamic effects of an excavator when slewing a freely suspended load at high rotations per minute (rpm). To achieve this, both the static load and horizontal centrifugal force from slewing this load were calculated for six randomly selected cases of an excavator, with different arm geometry configurations.FindingsThe results from the six cases are presented and a worked example of one is detailed to demonstrate how the results were derived. The findings reveal that the SWL quoted on an excavator’s lift rating chart considerably underestimates the extra forces experienced by the machine when an additional dynamic load is added to the static load whilst lifting and slewing a freely suspended load.Originality/valueThis work presents the first attempt to accurately model excavator stability by taking consideration of the dynamic forces caused by slewing a freely suspended load and will lead to changes in the way that industry develops and manages lift plans. Future research proposes to vary the weight of load, arm geometry and rpm to predict machine stability characteristics under various operational conditions, and exploit these modelling data to populate pre-programmed sensor-based technology to monitor stability in real time and automatically restrict lift mode operations.

Alternating magnetic force microscopy: simultaneous observation of static and dynamic magnetic field in three-dimensional space

In the scanning magnetic domain by using the conventional magnetic force microscopy (MFM), a laser beam reflection is used to detect the static magnetic force between probe and sample. Therefore, for the MFM, it is a challenge to directly detect the dynamic magnetic force between probe and sample under an external alternating-current (AC) magnetic field. In this study, it is proved that in an alternating magnetic force microscopy (A-MFM) a sensitive Co-GdO<sub><i>x</i></sub> superparamagnetic probe can be usedto detect the dynamic magnetic force under an external AC magnetic field (frequency <i>ω</i><sub>m</sub>). In the present method, the magnetization of Co-GdO<sub><i>x</i></sub> probe is modulated by an external AC magnetic field. Collecting <i>ω</i><sub>m</sub> and 2<i>ω</i><sub>m</sub> signals by using the combination of phase-locked loop (PLL) and lock in amplifiers can accurately represent the static (DC, which stands for direct current) magnetic field areas (the external AC magnetic field has no effect on the magnetized status of the sample) and dynamic (AC) magnetic field areas (the external AC magnetic field changes the magnetized status of the sample) of an anisotropic Sr ferrite sintered magnet at the same time, respectively. The Sr ferrite sample is a single-domain-type magnet where magnetization mainly changes via magnetic rotation. The A-MFM method can measure the strength and identify the polarities of the static magnetic field of sample with a DC demagnetized state. By modifying the traditional tapping-lift mode into a tapping-multiply lift mode, the A-MFM by using superparamagnetic tips can measure the static and dynamic magnetic field distribution in three-dimensional (3D) space. It is proved that the static and dynamic magnetic field as a function of the distance <i>z</i> between probe and sample are both expressed as <i>H<sub>z</sub></i>(<i>z</i>) = <i>H<sub>z</sub></i>(0)·exp(–<i>kz</i>). The experimental data are consistent with the previous theoretical calculations. The A-MFM can be used to study the dynamic magnetization process and to evaluate the magnetic homogeneity (microstructural homogeneity) of magnetic materials.

The Scheme of Tableware Cleaning Machine Pick-Up Plate Manipulator

This manipulator as an important part of the dish washer, mainly by hand, motion mechanism and control system structure, implementation will eat dish from containing fetching plates of box to take dish of mechanism movement. The hand is used to grab the plate, and the motion mechanism enables the hand to complete all kinds of rotation, movement or complex movements to achieve the specified action and change the position of the plate being grabbed. The lifting, stretching, rotating and other independent motion modes of the motion mechanism become the freedom degree of the manipulator. In order to grab all the plates in the box, the manipulator needs 5degrees of freedom, the more it does, the more flexible the manipulator will be, and the more versatile it is. The control system is to complete a specific action by controlling the moter with each degree of freedom of the manipulator. At the same time, it receives the information from the sensor to form a stable closed-loop control.

Imaging of electronical and magnetic properties on sub-10 nanometer scale with scanning force microscopy in ambient

ABSTRACTLimited by applicable force-detection techniques, imaging of electronical or magnetic properties on sub-10 nanometer scale with scanning force microscopy in ambient is challenging in experiment and equivocal in theory. In this paper, the multi-frequency method in AFM is employed to improve the lateral resolution of electrostatic force microscopy (EFM) and the sensitivity of magnetic force microscopy (MFM) under ambient conditions. A lateral resolution of sub-10 nm for EFM and a sensitivity that is superior to conventional MFM in lift mode are demonstrated experimentally. The mechanism of these techniques, which is attributed to the multi-frequency method and the reduced effective tip-sample distance, is also elucidated. The developed technique can be easily integrated to measure in situ both the electronical properties and the magnetic properties on sub-10 nanometer scale for optoelectronic materials.

Tuning the Copper Cluster´s Size By Electrodeposition from Perchlorate Aqueous Solutions. a Morphological Study through Current Density Transients and Atomic Force Microscopy

Introduction Copper nanoparticles (CuN) are widely used as cooling fluids for electronic systems [1], conductive inks [2], biosensors [3], electrochemical sensors [4], antimicrobial agents [5], among others. Also, CuN exhibit great catalytic activities, and nonlinear optical properties, which could result in many applications in optical devices and nonlinear optical materials, such as optical switches or photochromic glasses [5]. Currently the main methods to synthesize them include chemical reduction [6], in situ chemical synthetic route [7], and electrodeposition [8], among others. Specifically, electrodeposition is commonly used to synthesize nanoparticles because it is relatively simple and low cost procedure in comparison with other techniques [8]. However, it is important to remind that physical and chemical properties exhibited by CuN are highly dependent on their size and morphology by which, one of the main difficulty during their synthesis is tailoring and fine-tune the cluster’s size and the properties of these for a given application [9]. Thus, in the present work we analyze the possibility to get different cluster size maintaining constant the plating bath and modifying exclusively the applied potential on the electrode surface. Also, we carry out the morphological characterization of the CuN employing Atomic Force Microscopy (AFM) and its simulation through the current density transients. Methodology The copper electrodeposition onto HOPG electrode was carried out from a plating bath containing 0.01 M CuClO4 + 1 M NaClO4 at pH=5. All plating baths were prepared using analytic grade reagents and ultra pure water (Millipore-Q system) and they were deoxygenated by bubbling N2 for 15 minutes before each experiment. For these experiments, freshly cleaved HOPG surfaces were employed in each experiment. In all cases a graphite bar was used as counter electrode while an Ag/AgCl electrode (in saturated KCl), with a Luggin capillary was used as reference electrode. All experiments were carried out at 25 oC in unstirred solutions. The electrochemical experiments were carried out in an EPSILON potentiostat with the BASi-EpsilonEC software. Cyclic voltammetry was carried out in the 0.600 V to -0.800 V potential range. The characterization of CuN was performed with an Atomic Force Microscopy (AFM) a JEOL JSPM 4210 microscope in the lift mode. Results and discussion We analyzed the morphology of the copper deposits obtained when a potential step value in the range of [-0.075 - -0.175] V was applied during 5 seconds on the electrode surface. In Figure 1 is shown the experimental current density transient when a potential value of -0.075 V was applied. Also, note that under these conditions is possible to get the formation of homogeneous copper nanoclusters. In same Figure is reported the simulated density current transient and the morphology related to this transient. Observe that the simulated transient is similar to the experimental one, Moreover, the morphology predicted through this transient is similar to the experimental AFM image. Conclusions In the present work, it was tuned the copper cluster´s size by electrodeposition from perchlorate aqueous solutions applying different potential values on the electrode surface. The AFM study revealed the presence of copper clusters of nanometric dimensions. The simulation of the experimental transients, allow us to predict the morphology of the deposits through the simulated transients. Acknowledgements: LHMH gratefully acknowledges financial support from CONACYT (project CB2015-257823) and to the Universidad Autónoma del Estado de Hidalgo. References. S. Kim, S.R. Dhage, D.E. Shim, H.T. Hahn, Appl. Phys. A, 2009, 97, 791.Yonezawa, H. Tsukamoto, M. T. Nguyen, Adv. Powder Tech. 2017, 28, 1966.Heli, M. Hajjizadeh, A. Jabbari, A.A. Moosavi-Movahedi, Biosensors and Bioelectronics, 2009, 24(8), 2328.Veerappan, R. Devasenathipathy, S.-M. Chen, S.-F. Wang, P. Devic, Y. Tai, Electrochim. Acta, 2015, 176, 804.Wu, B.P. Mosher, T. Zeng, Mater. Res. Soc. Symp. Proc. 2005, 879, 1.Wu, B.P. Mosher, T. Zeng, J. Nanopart. Res. 2006, 8, 965.Mallick, M.J. Witcomb, M.S. Scurrell, Eur. Polym. J. 2006, 42, 670E. García-Rodríguez, L.H. Mendoza-Huizar, C.H. Rios-Reyes, Quím. Nova 2012, 35(4), 699.Xia, Y. Xiong, B. Lim, S.E. Skrabalak, Angw. Chem Int. Ed Engli. 2009; 48(1) 60. Figure 1

Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single superparamagnetic nanoparticle resolution

The detection of superparamagnetic nanoparticles by magnetic force microscopy (MFM) at the single particle level faces difficulties such as superposition of nonmagnetic signals caused by electrostatic interactions as well as reaching the resolution limits due to small magnetic interactions. In MFM the magnetic force is measured at a certain distance to the substrate following the topography measured in a first scan to avoid an influence of short range forces (lift mode). In this work we showed that performing MFM on superparamagnetic nanoparticles the increase of the tip-substrate distance above the nanoparticle in lift mode scans leads to a reduction of the electrostatic forces resulting in a positive phase shift in contrast to the negative phase shift of the attractive magnetic force. Identifying the electrostatic force in MFM on nanoparticles as a capacitive coupling effect between tip and substrate the origin of often seen topography mirroring in phase images of nanoparticles in general is theoretically explained and experimentally proved. Minimization of the capacitive coupling by adjusting the work function difference between tip and substrate as well as using an optimized tip allows the magnetic visualization of single 10 nm superparamagnetic iron oxide nanoparticles (SPIONs) at ambient conditions with and without an external magnetic field.

Symmetry Reduction and Shape Effects in Concave Chiral Plasmonic Structures

Chiral metamaterials have shown a number of interesting properties which result from the interaction of the chiral near-field they produce with light and matter. We investigate the influence of structural imperfections on the plasmonic properties of a chiral gold “gammadion”, using electron energy loss spectroscopy to directly inform simulations of realistic, imperfect structures. Unlike structures of simple convex geometry, the lowest energy modes of the ideal concave gammadion have a quadrupole and dipole character, with the mode energies determined by the nature of electrostatic coupling between the gammadion arms. These modes are strongly affected by structural imperfections that are inherent to the material properties and lithographic patterning. Even subwavelength-scale imperfections reduce the symmetry, lift mode degeneracies convert dark modes into bright ones and significantly alter the mode energy, its near-field strength, and chirality. Such effects will be common to a number of multitipped con...

Decision-Making Data: Expectations for Reproducibility of Lifting on Separate Days.

Purpose:The purpose of this study was to explore the difference in maximal lifting capability between 2 modes of lifting (traditional crate and XRTS Lever Arm) over multiple days. The differences in absolute strength values were compared with existing criteria for sincere effort during distraction-based lifting. In addition, rate of perceived exertion (RPE) is presented for the 2 modes of lifting on each day.Primary Practice Setting:Workers' compensation.Methodology and Sample:Forty-four subjects between the ages of 20 and 44 years participated in this study. Investigators established 1 repetition maximum (RM) for each subject performing the crate lift. Subjects were randomly assigned 5 weights ranging from 10% to 100% of their determined 1RM and asked to give their rating of perceived exertion after each lift. The same procedure was repeated 2–5 days later using the XRTS Lever Arm. Paired t tests and Spearman's correlation coefficient were used for data analysis. Alpha was set at less than .05.Results:There was a statistically significant difference (p < .04) between maximal lift values for the 2 lifting modes. The percent difference between the modes of lifting was 10.5% ± 6.4%. In addition, there was a positive correlation between the RPE on the 2 modes of lifting (p = .87).Implications for Case Management Practice:A functional capacity evaluation (FCE) is typically ordered after the completion of physical rehabilitation and before releasing a patient to full or modified duty. In addition to assessing the ability to function within normal job demands, an assessment of effort by the participant typically takes place during an FCE. Case managers and physicians are presented with information, allowing them to make comparisons between functional lifting abilities displayed during treatment sessions and the FCE. These comparisons may often take place with the subpoena of medical records and may be discussed during the deposition or trial process. If an FCE takes place at a different facility than the physical therapy or work conditioning treatment, 2 different modes of lifting may take place based on the equipment within each facility. The results of this study indicate that the 2 modes of lifting on separate days meet established criteria for lift comparison testing during FCEs.

Relationship between streamwise and azimuthal length scales in a turbulent pipe flow

The statistical relationships among the turbulence structures of the streamwise velocity fluctuations along the streamwise and azimuthal directions in a turbulent pipe flow were examined using direct numerical simulation data at Reτ = 3008. Two-point correlations of the streamwise velocity fluctuations showed a linear relationship between the streamwise and azimuthal length scales (lx and lθ), where lθ/lx = 0.07 along the wall-normal distance, indicating the long coherent structures called very-large-scale motions (VLSMs). The one-dimensional pre-multiplied energy spectra of the streamwise velocity fluctuations showed that the streamwise and the azimuthal wavelengths (λx and λθ) grew linearly along the wall-normal distance, λx/y = 20 and λθ/y = 7, respectively. The ratio between the two linear relationships was determined to be λθ/λx = 0.35, indicative of large-scale motions (LSMs). The energetic modes obtained from a proper orthogonal decomposition (POD) analysis using the translational invariance method showed that the averaged helical angles of the wall mode (ix &amp;lt; iθ; β &amp;lt; 0.1 rad, where ix and iθ are the streamwise and azimuthal mode numbers and β is the helical angle) and lift mode (ix ≥ iθ; β ≥ 0.1 rad) were related to lθ/lx = 0.07 (VLSMs) and λθ/λx ≈ 0.35 (LSMs), respectively. The superposition of the energetic POD modes showed the superimposed X-shaped patterns. The helical angle of the wall mode in the near-wall region was similar to that in the outer region, implying the existence of the VLSMs in the entire wall-normal distance. The LSMs showed more inclined X-shaped patterns. The LSMs were concatenated with the azimuthal offsets to form meandering VLSMs. Most of the VLSMs and LSMs in the near-wall region inclined smaller and larger than 10° (0.17 rad), respectively. In the core region, VLSMs were distributed more helically along the azimuthal direction due to the space limitations of the pipe geometry.

Dynamic loads during safety braking of the container with cargo

The article presents the results of the investigation into the effect of dry friction forces on the magnitude of the dynamic load acting on the rope in the process of safety braking. The equations for the analysis of the process of safety braking are presented. The analysis of the process of changing the forces in the rope showed that the maximum forces in the rope arising in the lifting mode of the load can be reduced by a factor of three of the forces of natural resistance to movement of the vessel. Modeled of sudden exertion of the brake force to the brake drum in the lifting mode. The results of mathematical modeling, presented in the form of graphs of changing efforts in the rope, confirm the theoretical results. The data obtained allows getting an expression for calculating the braking force, applied to the lifting container to eliminate head ropes during of safety braking.

Model of Motion of the Combined Manipulator

The combined manipulators composed of telescopic booms and rotary supports with movable in longitudinal vertical plane columns which provide an increased outreach of operative parts and a bigger service space are widely used in different branches of industry (engineering, transport). The article considers development of mathematical model of kinematic links motion of the combined manipulator with a column movable in longitudinal vertical plane. The mode of load lifting in a synchronous movement of boom and column from the position of picking the load up to the transport position was analyzed.

Model of Synchronous Motion of Links of the Combined Manipulator during Load Lifting

The combined manipulators composed of telescopic booms and rotary supports with movable in longitudinal vertical plane columns which provide an increased outreach of operative parts and a bigger service space are widely used in different branches of industry (engineering, transport). The article considers development of mathematical model of kinematic links motion of the combined manipulator with a column movable in longitudinal vertical plane. The mode of load lifting in a synchronous movement of boom and column from the position of picking the load up to the transport position was analyzed.

Influence of the phenomena occurring at the interface between L10-ordered-FePt and Fe on the coercivity behavior

L10-ordered FePt/Fe thin bi-layers were grown using a molecular beam epitaxy onto (100)-MgO substrates changing the soft Fe layer thickness. The study of the intermixing phenomena occurring at the hard/soft interfaces was carried out using surface Mossbauer spectroscopy. The magnetic properties of the samples were analyzed with a magneto-optical Kerr effect magnetometer. The surface morphology and the magnetic domains were analyzed with an UHV atomic and magnetic force microscopy in tapping and lift mode respectively.The present work clearly demonstrates that the degree of interface intermixing and reactions is the responsible for the coercivity behavior in exchange-spring magnets.

Secondary resonance magnetic force microscopy using an external magnetic field for characterization of magnetic thin films

A bimodal magnetic force microscopy (MFM) that uses an external magnetic field for the detection and imaging of magnetic thin films is developed. By applying the external modulation magnetic field, the vibration of a cantilever probe is excited by its magnetic tip at its higher eigenmode. Using magnetic nanoparticle samples, the capacity of the technique which allows single-pass imaging of topography and magnetic forces is demonstrated. For the detection of magnetic properties of thin film materials, its signal-to-noise ratio and sensitivity are demonstrated to be superior to conventional MFM in lift mode. The secondary resonance MFM technique provides a promising tool for the characterization of nanoscale magnetic properties of various materials, especially of magnetic thin films with weak magnetism.

Carrier trapping study on a Ge nanocrystal by two-pass lift mode electrostatic force microscopy

Trapped charges inside an isolated germanium nanocrystal (Ge NC) have been studied by two-pass lift mode electrostatic force microscopy (EFM) measurements at room temperature. From visualized EFM images, electrons and holes were proven to be successfully injected and trapped in the Ge NC and distributed homogenously at the edge of its truncated spherical morphology. The Ge NC is found to have iso-potential surface and behave as a conductive material after being charged. It is also shown that the dominant charge decay mechanism during discharging of Ge NCs is related to the leakage of these trapped charges. A truncated capacitor model is used to approximate the real capacitance between the tip and Ge NC surface and to quantitatively study these trapped charges. These investigations demonstrate the potential for Ge nanocrystal memory applications.

DC–DC converter with high voltage gain and reduced switch stress

In this study, a novel high step-up dc–dc converter with high voltage gain and reduced switch stress is proposed. Utilising the coupled inductor to replace the boost inductor for high step-up converter is widely used in the application of high voltage gain converter. It can not only achieve a high voltage gain but also use the core effectively by using the coupled inductor. The techniques of voltage lift, voltage multiplier and clamp mode are also used in the proposed topology. Furthermore, the proposed converter can avoid the extreme duty cycle that will cause a lot of conduction losses. The leakage inductance energy of the coupled inductor will cause a huge voltage on the components of circuit, so that it needs to choose the components with high voltage and current ratings; then the efficiency is reduced and the cost is increased. The converter proposed in this paper can not only recycle the leakage inductance energy to the output but also increase the efficiency. A 300 W prototype converter which is implemented with an input voltage of 26 V and an output voltage of 400 V will demonstrate the effectiveness of this proposed converter.

자동차 엔진용 2단 가변밸브 기구의 스위칭 시스템 동적 거동에 관한 연구

Abstract : Variable valve actuation system is one of the widely used techniques to improve the fuel efficiency and power of automotive engines. 2-step variable valve actuation systems are also paid attention for the application to direct acting type valve train systems. Besides its advantages in size, weight, relatively simple structure, ets, however, 2-step variable valve actuation system has inherent disadvantages in dynamic instability of switching system to alter discontinuous lift modes. In this study, both experimental and analytical studies are performed to understand the dynamic behavior of a switching mechanism of a 2-step variable valve actuation system, and present a design method to improve its dynamic instability. Key words : 2-step variable valve(2 단 가변밸브), Automotive engine( 자동차 엔진), Latching system( 전환 시스템), Switching system(스위칭 시스템) Nomenclature 1) M SP : mass of switching pin, kgM LP : mass of lock pin, kgM RS : mass of return spring, kgk RS : stiffness of return spring, N/mc

Adhesive Forces Between Aromatic Molecules and Graphene

Adhesive forces were investigated in a computational study for the complexes of graphene with each of the four adsorbates, benzene, anthracene, pyrene, and tetracene, by using the DFT method B3LYP and the semiempirical method DFTB, together with empirical dispersion corrections. The four aromatic molecules differ in size and flexibility. Whereas the adhesion energy (for complete separation) is independent of the way an adsorbed molecule is separated from graphene, the maximum adhesive forces depend strongly on the way the adsorbate is lifted. We investigated, therefore, four lifting modes: in rigid vertical lifting, all atoms of the adsorbate are pull-off points; in flexible central lifting, the pull-off points are in the middle of the adsorbate; in both rigid and flexible terminal lifting, the pull-off points are at one end and the adsorbate is regarded as being either rigid or flexible. For the systems investigated, we find that, for both the adhesion energies and the maximum adhesive forces, the DFTB results are at most 10% lower than the corresponding DFT results. For small or rigid molecules like benzene and pyrene, there is no significant difference between rigid vertical and flexible central lifting. For a flexible molecule like tetracene, the difference of the maximum adhesive force can be up to 70%. Terminal lifting consists of two subprocesses. For the second subprocess, both the adhesion energy and the maximum adhesive force are essentially unchanged across all four adsorbates; for the first subprocess, however, we find a pronounced size dependence of the adhesion energy.

Planning Design of Stereo Parking Lot Based on Bionics Principle

The old town of the city, which has complicated network, is difficult to reform. Because of the traditional flat's low utilization of parking space and shortage of parking spaces, it is urgent to improve the existing public parking facilities for enhancing the status of the old area traffic and promoting the economic development of the old city. On the basis of the thought of double helix bionic structure, this article is to design a new energy-saving convenient parking building. Taking the double helix structure of DNA as the design concept, it takes the advantage of the double spiral of extraction track, and telescopic parking device of intelligent multiple angle, rotating parking platform, interactive extraction of vehicle system and a model for effective utilization of energy to improve the vertical lifting mode of the original stereo parking lot. Taking the characteristics of renewable energy and kinetic energy into consideration, it analyzed the available energy stability and the cost of using index, from the angle of reducing the output operation power and saving the energy. Research results can make the stereo garage's intelligence operation possible, parking access intelligence operations and be able to largely providing ground spaces, and it can greatly provide ground parking capacity, which improves the difficult parking problem in central business district effectively.