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A centrifugal rice seeding spreader with a baffle ring was designed for an unmanned aerial vehicle (UAV). Rice seeds ejected by a rotating disc are caused to rebound by a baffle ring, to produce a non-hollow, fan-shaped distribution at field level. Three factors produce influences on the distribution, and they are the rotation of the disc, UAV flying height and the angle of the baffle ring. The discrete element method (DEM) was used to simulate the range of the three factors and to explore their influences. Experiments were then conducted using a central composite design (CCD) approach to optimise these three factors. Simulation results showed that the influence of the three factors on distribution uniformity was in the order (most to least); UAV flying height, sowing disc rotation and baffle ring angle. Optimal parameters for the most uniform distribution in simulations were; sowing disc rotation 600 rpm, flying height 2.1 m and the baffle ring angle 26°. The coefficient of variance (CV) achieved was 21.39%. The bench tests were implemented where a CV of 23.24% CV was obtained. Field tests were carried out, and the CV values between 22.21% - 32.90% were obtained because of the influence of the wake of the drone's propellers. At optimal parameters, the crop yield in the field reached 76,66 kg ha−1 in the field experiment.

To widen the new way of thinking and to explore a new technology of rice planting, industrialized rice production is an advanced rice planting method. All processes of rice growth were finished in factory and they provided proper growth conditions (including light, CO2 concentration, temperature, moisture and minerals) on the base of different growth stages. This paper illustrated the theory of rice growth in factory, the processes of rice cultivation and fundamental structure of rice factory. It combined natural conditions with artificial environment to create an ideal rice growing environment. Rice cultivation’s cycle in factory was shortened and normally one day was divided into 2 - 3 special days. It could be continuous production and prevented rice planting from being affected by external conditions. Industrialized rice makes full use of energy on the basis of sunray and artificial supplies to increase the rice yield and it will start a revolution of rice planting and solve the problem of food safety.

Room temperature liquid metal (RTLM)-related electronics has recently been found increasingly important in a wide variety of emerging areas. In particular, printable liquid metal ink opens the way for direct writing of electronics spanning form microscale to even nanoscale. However, such fluid-like circuits also raised important fundamental as well as practical issues for solving. A big issue facing its future large-scale application is that the failure features of the conductive wires under electrical current densities are not clear. Here, we discovered for the first time that a liquid metal thin film would be broken by the so-called electromigration effect as the applied current increases to a critical magnitude. A theoretical model was established to preliminarily interpret the phenomena and the related effects. The break-up effect in the liquid metal-based circuits could be one of the major hurdles that must be tackled with caution in the research and application of future liquid metal technologies, especially for the printed microelectronics thus enabled.

We report beta-detected NMR (β-NMR) measurements on a 50 nm thick platinum (Pt) film grown on a magnesium oxide (MgO) substrate. The frequency of the β-NMR resonance in Pt was compared to the MgO reference frequency to estimate the Knight shift at various temperatures (100-300 K). The Knight shift was found to be negative and strongly temperature dependent. The implications are discussed and compared to other transition metals that have been studied via β-NMR previously.

The relationship between the direction of the magnetic line and the circulating supercurrent of a vortex in type-II superconductors is discussed. Contrary to the views presented in some articles, we will make it clear that the magnetic line and the circulating supercurrent of a vortex have a “right hand” relationship by considering basic electrodynamics and the lowest energy principle.

The entangled states that include every physical properties of particles would be important for both theoretical and applied physics. However, the existence and properties of such entangled states are unclear at present. Here we theoretically show that a particle-antiparticle pair can form the so-called packaged entangled states which encapsulate all the necessary physical quantities for completely identifying the particles. The particles in the packaged entangled states are indeterminate and exhibit unusual properties. Thereafter, we discussed the possible applications of these new entangled states, i.e., the protocol for teleporting the entire quantum state of a particle (or an antiparticle) to an arbitrarily large distance without a classical channel, transfer of the new entangled states from a particle pair to another particle pair, and new interpretation to the matter-antimatter asymmetry of the observable universe., Comment: 21 pages, 3 figures

Mango (Mangifera indica L. cv. Hongxiangya and Wacheng) was chosen to study the effect of postharvest biological characters in different storage conditions. The determining items included respiratory rate, total sugar, vitamin C (Vc) content, firmness, polyphenol oxidase (PPO) and peroxidase (POD). The results showed that both 8 and 11C were the better storage temperatures, and the storage life would last 50 days in this situation. The respiration rate increased quickly between the 16th to the 22nd days; the peak values were the 28th and 25th days at 8C for Hongxiangya and Wacheng, respectively. The flesh firmness decreased dramatically at 6 days after harvest. Total sugar content, Vc content, PPO and POD increased at first and then decreased. The color changed from green to yellow with the increase of carotenoids content. After treatment with thiabendozole and iprodione, the number of rot fruits was markedly lower than the other treatments. The best temperature is 11 and 14C for Hongxiangya and Wacheng, respectively. The rot rate is 6.77 and 8.33% with 1,000-ppm iprodine treatment after 50-days storage.

The vortex energy of type-II superconductors in mixed state is discussed based on the assumption that vortex can undergo quantum effect. The Hamiltonian of an isolated vortex of type-II superconductors in lower magnetic fields is calculated from the elasticity of vortex within the framework of weak collective pinning theory. The results indicate that the vortex can be described using the eigenvalue of a harmonic oscillator and the eigenvalue of the vortex energy can be reduced by the action of Lorentz force of the current acting on the vortex. The quantum effects of vortices in higher magnetic fields are also studied and two particular directions of the dispersion models of the two-dimension triangular vortex lattice are given.

Y-deficient Y1−xBa2Cu3O7−δ films (x=0, 0.05, 0.1) are fabricated on LaAlO3 (0 0 1) single crystal substrates using trifluoroacetate-based metalorganic deposition (TFA-MOD). X-ray diffraction patterns show that all films are highly c-axis oriented. The measurement of the resistance transition broadening under the applied magnetic field perpendicular to the surfaces of YBCO films indicates that a slight Y-deficiency (Y0.95Ba2Cu3O7−δ) in YBCO films is favorable to improve flux pinning. However, a further increasing of Y-deficiency (Y0.9Ba2Cu3O7−δ) leads to the degeneration of flux pinning abilities. The improvement of flux pinning may be related to the BaCuO2 phase particles with submicrometer scale or the defects induced by slight Y-deficiency.

Magnetic flux pinning classification based on the pinning center size is found to be imperfect because of the proximity effect of superconducting state. The application of this idea to the Dew-Hughes model shows that the eight flux pinning functions in it are linearly dependent, which implies that some of these pinning mechanisms are not the primal ones, but a combination of others. Based on the physical considerations, ‘core, normal, surface pinning’ and ‘core, normal, point pinning’ are abandoned. A pinning function that is related to the self-field critical current is induced. Then seven linearly independent pinning functions are picked out to represent the seven primal pinning mechanisms, respectively. The application of these seven functions to the experimental data shows that they contribute to a better general description of the complex mechanism of the pinning of the superconductors.

The samples of Mg deficiency with different Mg nominal content (Mg1-xB2) are prepared by the solid-state reaction method at the sintering temperatures of 900 and 640 degreesC. The effects of Mg deficiency on the structure and superconducting properties are investigated by the Rietveld refinement of X-ray powder diffraction and the resistance measurement, respectively. The results show that the lattice parameters of the samples sintered at different temperatures are of a similar variation, i.e., a decreasing and c increasing with increasing x, respectively. T-c of the samples decreases with increasing x and the maximum T-c variation of DeltaT(c)(T-c(max) - T-c(min)) similar to 2 K is observed for samples sintered at high temperature. It is concluded that the nominal Mg content reduction does not give rise to serious Mg deficiency and slight Mg deficiency does not result in a remarkable change of T-c and normal state properties of the samples. (C) 2002 Published by Elsevier Science B.V.

The vortex hopping motion in a type-II superconductor determines the current-carrying ability and consequently the application fields of the superconductor. However, it is not clear how the vortices hop between the different pinning regions in the superconductor. Here we proposed that there should be magnetic \textit{flux exchange} between two contacting pinning regions. A system of differential equations was constructed to describe the flux exchange phenomenon. The qualitative analysis methods were used. The approximate numerical solutions and approximate analytical solutions of the system were obtained. The results show that the flux exchange reduces the internal field in a weak pinning region, but increases the internal field in a strong pinning region. Moreover, the flux exchange phenomenon is strongly influenced by the superconductor's geometrical size.

Vortex penetration and flux relaxation phenomenon carry the information about the pinning ability, and consequently current-carrying ability, of a type-II superconductor. However, the theoretical descriptions to these phenomena are currently limited to the cases with special initial conditions. A generalization to the recently developed infinite series models is presented here. It is shown that one can convert a vortex penetration process with a non-zero initial internal field into a process with a zero initial internal field by introducing some time parameters. Similarly, one can also convert a flux relaxation process starting with an arbitrary internal field into a process starting with a melting internal field by introducing a virtual time interval. Therefore, one can predict the melting internal field (or critical current density) from a flux relaxation process starting with a lower internal field. Finally, it is shown that the vortex penetration process in an ideal superconductor is strongly time dependent because of the surface barrier and internal field repulsive force. But the flux relaxation process does not occur in the ideal superconductor., 9 pages, 3 figures

The information about the current-carrying ability of a type-II superconductor can be obtained by studying the flux relaxation and vortex penetration phenomena in the superconductor. In early studies, the infinite series models of the flux relaxation and vortex penetration phenomena were constructed at a vanishing current density and vanishing internal field, respectively. However, this is not the only possibility. Here it is shown that one can reconstruct the theoretical models at the critical points. The new polynomial model of the flux relaxation (vortex penetration) phenomenon was constructed by expanding the vortex activation energy as an infinite series of the current density (internal field) about the critical current density (equilibrium internal field). The unification of the polynomial models was proposed. The inverse model of the flux relaxation (vortex penetration) phenomenon was also constructed by expanding the vortex activation energy as an infinite series of the inverse current density (inverse internal field) about the critical current density (equilibrium internal field)., Comment: 10 pages, 2 figures

Vortex penetration affects the stability of a superconducting system and limits the possible application of the system. However, the mathematical description to this phenomenon is currently unavailable. Here I present a mathematical model in which I consider the effects of bulk pinning and internal field repulsive force on vortex hopping. Thereafter, I proposed a series expansion to the activation energy and derived a general formula for describing the time dependence of the vortex penetration process. With these formulas, I can analyze the experimental data and calculate the activation energy of the vortex penetration phenomenon. The results are accurate for the time dependence of the internal field measurements in a $Bi_2Sr_2CaCu_2O_{8+x}$ superconductor., Comment: 5 pages, 1 figure

Studies of the persistent current relaxation of ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ ring-shaped thin films as a function of oxygen concentration (with 24 increments in $\ensuremath{\delta}$ every $\ensuremath{\sim}0.021$, over a range between 0.03 and 0.55) allowed us to construct the $(\ensuremath{\mu},\ensuremath{\delta})$ phase diagram where the exponent $\ensuremath{\mu}$ characterizes the pinning ability and the nature of the vortex structure. The reduction of the hole-doping level (an increase in $\ensuremath{\delta}$) transforms the vortex structure from quasi-lattice into a glass and subsequently into a pinned liquid phase. These vortex phases self-organize and produce relaxation plateaus in regions between steplike changes in the dependence of relaxation kinetics on hole doping.

Depth-controlled $\ensuremath{\beta}$-NMR was used to study highly spin-polarized $^{8}\mathrm{Li}^{+}$ in a Cu film of thickness $100\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ deposited onto a MgO substrate. The positive Knight shifts and spin relaxation data show that $^{8}\mathrm{Li}^{+}$ occupies two sites at low temperatures, assigned to be the substitutional $(S)$ and octahedral $(O)$ interstitial sites. Between 50 and $150\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, there is a site change from $O$ to $S$. The temperature dependence of the Knight shifts and spin-lattice relaxation rates at high temperatures, i.e., when all the Li are in the $S$ site, is consistent with the Korringa law for a simple metal.

A ferrofluid is a mixture that exhibits both magnetism and fluidity. This merit enables the ferrofluid to be used in a wide variety of areas. Here we show that a floating ferrofluid bridge can be induced between two separated boards under a balanced external magnetic field generated by two magnets, while a flying ferrofluid bridge can be induced under an unbalanced external magnetic field generated by only one magnet. The mechanisms of the ferrofluid bridges were discussed and the corresponding mathematical equations were also established to describe the interacting magnetic force between the ferro particles inside the ferrofluid. This work answered a basic question that, except for the well-known floating water bridges that are related to electricity, one can also build up a liquid bridge that is related to magnetism.

A superconducting ring could be used to simulate the supercurrent conduction, and its interaction with magnetic vortices in a superconducting solenoid, allowing one to investigate the nature of the vortex structure and its pinning in the presence of the persistent supercurrent. The dissipation of the persistent supercurrent has been studied in a ring-shaped high purity single crystal of Bi2Sr2CaCu2Ox in order to obtain the information about the exponent μ, a parameter in the scaling relation between the effective energy barrier against vortex motion Ueff and the persistent current density J. The measurements of the persistent supercurrent decay show a transition from a strongly nonlogarithmic to a logarithmic decay regime with an increasing temperature. In response to a small increase in the concentration of oxygen vacancies μ decreases in the logarithmic decay regime but remains almost constant in the nonlogarithmic one.

We report measurements of the anisotropic magnetoresistance (AMR) of epitaxial thin film and polycrystalline samples of La0.65Ca0.35MnO3. Near the metal-insulator transition (MIT) temperature the AMR of both polycrystalline and thin film samples exhibit a peak. However at temperatures well below the MIT, the AMR of the polycrystalline samples is much larger than that of the epitaxial films, suggesting that the anisotropy of the spin-polarized tunneling of the charge carriers across grain boundaries in a magnetic field is responsible for the observed low temperature behavior.

The authors investigated the anisotropic magnetoresistance (AMR) in ultrathin La-based manganite films grown on various substrates. It was found that depending on the strain state, the AMR in some of these systems exceeds 100% and can even change sign. These changes are very dramatic when compared to the few percent change in AMR in conventional ferromagnets. The mechanism behind these large changes in the AMR is discussed.