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[Objective] The biological characteristics of different attached algae were determined and the relation between water quality indicators and algae biological characteristics were analyzed in order to provide scientific support for screening scientifically reasonable attached substrates and enriching the growth of attached algae. [Methods] The biological characteristics of algae attached to three different building material substrates (granite, polyethylene mesh, wood) were analyzed using simulation experiments. The types of attached substrates having good effects and easy resource utilization were selected. [Results] The periphytic algae communities attached to granite and wood substrates were more stable, and had better biological characteristics and more functional algae species, and thereby were more conducive to providing an ecological effect of periphytic algae in the water environment. [Conclusion] The granite substrate was considered to be the most suitable substrate among the three tested substrates because of its ready availability and ease of use.

The preparation of thin ferromagnetic films with thermally stable properties in the high frequency gigahertz range is crucial for applications in different advanced devices. However, it is a challenge to attain such films as the mechanism and correlation between the crystallographic structure and dynamic magnetic properties remain unclear. Herein, through an appropriate annealing process involving a temperature of 510-580K and an applied strong magnetic field of 10 kOe along the easy-axis of electrodeposited FeCo films, magnetic properties of the films (300-450 nm) in the gigahertz range are significantly improved. Typically, the magnetic soft nanofilms display highly stable dynamic microwave properties from room temperature to 420 K, even in the presence of a high frequency of ∼1.5 GHz and a large magnetic permeability of ∼460 (the maximum value in real part). The origin of the high thermal stability is attributed to the recrystallized uniformity in crystalline orientations and larger particle sizes after the annealing, which leads to slightly increased anisotropy, stress, Curie temperature, and difference in the magnetic coercivity between the easy and hard axes for the crystalline films, thus giving rise to the steady static magnetic properties (e.g., magnetic moment of 2.02-2.05 T) against environmental temperature fluctuation. This is in contrast to conventional as-prepared thin films without annealing or annealed in a transverse applied field. This method can be applied to other ferromagnetic films to improve their thermal stability for the utilization in various high frequency devices. [ABSTRACT FROM AUTHOR]

In this study, sheet mica was explored as an alternative substrate for thin film deposition due to its unique layered structure and atomically flat surface. Static magnetic properties and microwave permeability of sputtered FeCoN films on mica with and without SiO2 under-layer were examined. In-plane isotropy and a large coercivity of 70 Oe were observed for the film directly deposited on mica substrate. With the insertion of 40 nm SiO2 under-layer between the film and mica substrate, well-defined in-plane anisotropy is formed due to the significant reduce in film residual stress, associated with a 3 Oe coercive force along easy axis. As a result, excellent microwave properties have been achieved and are comparable with the same film on Si substrate. Moreover, the permeability spectra are surprisingly stable from room temperature up to 390 K. Mica is proved as a promising substrate for magnetic films with high microwave performance, which is a great advantage for practical applications. Furthermore, our results provide an effective way to reduce the residual stress in sputtered films. [ABSTRACT FROM AUTHOR]

In this work, we deposited FeCoN thin films by reactive dc magnetron sputtering under various deposition powers. Composition, microstructure, static magnetic properties, and microwave permeability of as-sputtered films were examined. The permeability spectra were theoretically analyzed based on LLG equation. When high deposition power was applied, μ0' improved significantly due to the increased Mi and decreased Hk. On the other hand, the damping coefficient λ increased with the power, which resulted in the widen permeability spectra. The physical origin of the influences should be related to the change in the film composition and microstructure, which have immediate impact on static magnetic properties and damping effect of the film. [ABSTRACT FROM AUTHOR]

In this paper, a MMP algorithm is proposed. Compared with the classical algorithm, the proposed algorithm reduces the noise threshold of stably extractable parameters by 15 dB and reduces the computing time by ten or more. As an efficient way to interpret the measurements of high-frequency Inverse Synthetic Aperture Radar (ISAR), the Geometric Theory of Diffraction (GTD) model provides concise features of complex targets. However, the existing parameter extraction algorithms suffer from high computational complexity and poor ability against noise. To solve these challenges, a Maximum Matching Pursuit (MMP) algorithm is proposed in this paper. The proposed algorithm achieves parameter estimation by searching the maximum value of the dictionary matrix and observation signal matrix product. Compared to the classical OMP algorithm, the proposed algorithm significantly reduces the computational complexity by estimating params without cycles. To demonstrate the reconstruction efficiency of the improved algorithm, the Root-Mean-square-error (RMSE), and the computer time of the proposed algorithms are compared with the original algorithms, such as the OMP and the Estimating Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm, under different Signal-to-Noise-Ratio (SNR). The simulation results show that the proposed algorithm reduces the noise threshold of stably extractable parameters by 15 dB, reducing the computing time by ten or more.

The magnetostriction coefficient (λs) of ultrathin sputtered polycrystalline as-deposited and annealed Ta/Ni81Fe19(t)/Ta films was studied as a function of the thickness. λs and magnetoresistance (MR) of bottom-type spin valves (SVs) with nano-oxide layer (NOL) added in the pinned layer were investigated by using NiFe, Co90Fe10, and CoFe/NiFe/CoFe layers as free layer (FL), respectively. λs of SV with NOL increased slightly except that of CoFe FL. NOLs were added at different positions to study the effects of NOL on λs of CoFe FL. All λs of CoFe FL change from negative to positive and its absolute value also increases significantly with CoFeOx related NOL added below. Our λs and surface roughness results indicated that the structure of the film not the roughness dominates λs of ultrathin FL in SVs. [ABSTRACT FROM AUTHOR]

Magnetization properties of magnetic nanowire arrays are studied on various ferromagnetic materials grown in anodic alumina (alumite) and track etched polycarbonate (PCTE) membranes by pulsed electrodeposition. Magnetization curves were measured as functions of wire material, field orientation, and wire length. The coercivity (H[sub c]) and remanent squareness (S) of the various wire arrays were derived from hysteresis loops as a function of angle (θ) between the field and wire axis. For PCTE membranes, H[sub c](θ) curves for CoNiFe, NiFe, and Co nanowire arrays all show an otherwise-bell-type variation, while they change shapes from the otherwise bell to bell type for Ni nanowire arrays as the wire diameter decreases to 30 nm. These characteristics can be understood based on different magnetization reversal mechanisms of small wires. The effect of magnetostatic interaction among wires on the magnetic properties was examined by changing the wire lengths in alumite membranes. It is found that the interaction reduces H[sub c] and S values significantly and may cause the overall easy axis change from parallel to perpendicular to the wire axis. However, the interaction is much weaker than expected from an independent precession theory. The strong coupling among the wire may also induce a change of magnetization reversal mechanism. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Field dependence of low frequency noise in tunnel magnetoresistance (TMR) heads with different barrier materials of TiO2, Al2O3, and MgO has been studied. It is found that for MgO-TMR heads, the noise amplitude increases as the sensor is driven from parallel to antiparallel magnetization configurations. However, this field dependence of the noise is not magnetic in origin and can be accounted for by the coherent tunneling mechanism in MgO-TMR heads. For TiO2- and Al2O3- TMR heads, low frequency noise is generally independent of magnetic field when the heads are biased properly by hard bias. A noise spike related to a resistance jump in the transfer curve is measured in a head without proper hard bias. Field-dependent low frequency noise is observed for TMR heads without hard bias. The noise amplitude follows the sensitivity function of the sensor and can be attributed to the thermally activated magnetization fluctuations. Spin transfer (ST) effect on low frequency noise was examined by noise measurements of field dependence at different current directions. Extra noise appears when the TMR head is in antiparallel magnetization configurations. The results suggest that the ST-induced extra noise can be either pure 1 / f noise or the combination of both 1 / f and random telegraph noises. [ABSTRACT FROM AUTHOR]

Multi-row-per-track discrete bit patterned media with interleaved bits have been fabricated on granular perpendicular media disks by focused ion beam and tested by magnetic force microscopy and spinstand tester. It was found that sub-100 nm patterned magnetic islands showed single domain behavior and narrowed switching field distribution. We further demonstrate from captured spinstand readback waveforms the concept of recording two rows of interleaved dot bits as one track. In addition to overcoming the down track patterning resolution limit, the proposed concept patterned media provide many other advantages including higher data rate for read/write, a flexible bit aspect ratio (BAR)≥2 design for better integration with head design and servo control, as well as allowing the use of wider write pole to improve writing efficiency for high density recording. [ABSTRACT FROM AUTHOR]

Two series of Co2MnAl (CMA) and Co2MnAlO (CMAO) thin films deposited on Si (100) coated with thermo-SiO2 by using two CoMnAl targets were studied. One target is oxygen-free and the other one contains 0.8% oxygen. The properties of the two series CMA (O) films strongly depend on deposition conditions and seed layers. The oxygen impurity is a key factor to influence the properties. It would obviously increase the thickness of magnetic dead layer, weaken the magnetic anisotropy, and significantly decrease the spin polarization in CMA film. The magnetoresistance ratios of IrMn pinned top-type magnetic tunnel junctions by utilizing CMAO/CMA as the bottom ferromagnetic electrode were 19% and 68%, respectively. [ABSTRACT FROM AUTHOR]

The peak value (PSDp) from power spectral density (PSD) curves was obtained as a function of burning current before and after the breakdown in tunnel magnetoresistive (TMR) heads. The obtained PSDp versus current curves can be classified into two categories. For one set of TMR heads, an abnormal peak was observed just before the breakdown of TMR heads. For another set of TMR heads, PSDp shows a nearly linear current dependence as expected from the mag-noise theory. After the pinhole growth, the abnormal PSDp peak disappears, implying that it is related to the pinhole-free barrier. Spin transfer effect was examined to understand the abnormal increases in PSDp by both reversing current direction and reducing measuring current. The result shows that the spin transfer effect is not important for the presence of the abnormal increase in PSDp. In spite of the lack of a full understanding, we will give discussions on possible mechanisms. [ABSTRACT FROM AUTHOR]

Aiming at the automobile gearbox shell local deformation failure problem,an evaluation method based on the dynamic stiffness of the critical point of the target shell is proposed. In a front transverse gearbox as the research object,using Hyperworks software to establish the finite element model of shaft hole in the key points of the incentive target the input method of transfer function,the vibration characteristics,vibration frequency analysis of vibration response of transmission after strong shell,obtained after the transmission housing mounting point acceleration frequency response curve and the frequency response curve of dynamic stiffness. Furthermore,the structure of the rear shell of the transmission is improved,and the improved structure is verified by software. Research shows that the dynamic stiffness of the frequency response curve evaluation method is an intuitive and accurate relationship with the deformation response of shell structure,can accurately find the effective method to frequency range and location of improved housing, and the housing structure improvement can effectively improve the vibration characteristics of the shell structure.

Aiming at the problem of radiated noise in automobile transmission housing, a method to find the exact location of effective reinforced concrete parts by using modal acoustic contribution analysis and panel acoustic contribution analysis is proposed. In this paper, the sound pressure curve and its peak frequency of the transmission shell are obtained by using the analysis method of acoustic boundary element. Then, by analyzing the contribution of modal acoustics at peak frequency, the modal order of the larger contribution to the noise is obtained, and the local area with large acoustic contribution is obtained from the modal cloud. Finally, the localized region of the acoustic contribution is analyzed by the acoustic section contribution analysis, so as to find out the acoustic Contribution to the larger and need to improve the specific parts. Furthermore, the structure of the transmission case is improved, and the improved structure is verified. The study shows that the method of reducing the radiation noise of the shell by means of modal acoustic contribution analysis and panel acoustic contribution analysis is an effective method to find out the specific parts of the shell that need to be improved intuitively and accurately, and the improved shell structure can be effective improved the noise characteristics of the shell.