Relief Depth Research Articles

Complementary Sampling Methods to Inform Ecosystem-Based Management of Nearshore Fisheries

Area-based fishery management and ecosystem-based management strategies are considered beneficial marine resource management tools, but they require finite information about the structure and function of ecosystems to evaluate populations and describe the effects of fishing on ecosystems. The required information is not likely to be obtained from sporadic, fishery-dependent data collected from data-poor fisheries, and funding constraints preclude extensive fishery-independent surveys. This situation has led to an interest in relating or combining information from a variety of disparate sampling methods. From 2003 to 2006, we investigated the relationships between estimates of catch per unit effort (CPUE) and the abundance of fishes generated from typical nearshore commercial fishing operations and estimates of density and abundance derived from scuba surveys in the same locations. The relationships between CPUE and the density estimates derived from different sampling methods were found to be statistically significant in the case of many of the common species sampled across sites in Carmel Bay, California. The compounding effects of within-sample variance and the error associated with the regression equations, however, would result in poor confidence in the values translated from one sampling method to another. Different sampling methods may provide reasonable estimates of population trends, but they are sufficiently different and variable as to preclude the use of a scaling factor to standardize population estimates among sampling methods. Also, the differences in species composition (i.e., relative CPUE or density among species) produced by each sampling method were significant and were also affected by habitat relief and sample depth. Nonetheless, our results suggest the value of a cost-benefit analysis that would allow managers to design optimal sampling strategies for characterizing CPUE relationships within a region of interest. A sampling program that benefits from the complementary strengths of fishing gear and scuba sampling will probably result in the most comprehensive description of nearshore fish assemblages.

Fast Tool Servo-based Ultra-precision Diamond Machining of Fresnel Micro-structured Surface and Its Control Technology

The ultra-precision diamond machining of micro-structured surface is a new research interest arising in recent years abroad, however, it is just in its infancy for Chinese researchers in this field. Moreover, because of the limitations of advanced machine tools, it is extremely difficult to carry out such studies. In order to solve this problem, an ultra-precision machine tool with fast tool servo (FTS) is designed. Additionally, variable-structure sliding-mode control (VSSMC) strategy designed according to adaptive index reaching law is applied to the control of FTS, and a comparison test under different control strategies is conducted. The experimental results that it is found that the response time for both VSSMC and PID is similar, but for VSSMC, there is almost no overshoot and the sine tracking result is more effective than PID control algorithm. At last, the experiment on ultra-precision diamond turning of Fresnel micro-structured surface is performed by using VSSMC, and a Fresnel micro-structure with a radius of 5 mm, relief depth of 10 μm and surface roughness of 35 nm is successfully machined.

Superhydrophobic surface structures in thermoplastic polymers by interference lithography and thermal imprinting

We present a method to produce superhydrophobic surfaces in thermoplastic polymer substrates. The method involves the creation of a nickel stamp using a customized laser interference lithography technique and electroplating processes. This stamp is used to emboss sub-micrometer periodic structures into the thermoplastic. The modified surface is coated with a hydrophobic plasma-polymerized hexafluoropropene layer. Surfaces with different periodicity and relief depth were created. On the surface with the highest aspect ratio, advancing water contact angles of 167° were measured with a water contact angle hysteresis of below 5°.

Synthesis and photoinduced surface relief grating formation of novel photo-responsive amorphous molecular materials, 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-cyanoazobenzene and 4-[bis(9,9-dimethylfluoren-2-yl)-amino]-4′-nitroazobenzene

Novel azobenzene-based photo-responsive amorphous molecular materials, 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-cyanoazobenzene and 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-nitroazobenzene, have been synthesized and the formation of surface relief grating on their amorphous films has been investigated. It was found that a relatively large surface relief grating could be inscribed on both amorphous films upon interference exposure to the writing laser beams. The modulation depth of the surface relief grating inscribed on the amorphous film of the cyano-substituted material was found to be larger than that inscribed on the film of the nitro-substituted one and seemed to be comparable to that inscribed on the amorphous film of the parent material, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene. These results were discussed from the viewpoint of their trans–cis photoisomerizations as amorphous films and glass-transition temperatures.

A quick algorithm of exposure distribution for fabrication of micro-optical structures

An approximate algorithm of exposure distribution on photoresist for the case of large exposure dose is obtained on the basis of the algorithm reported in [X. Dong, C. Du, S. Li, C. Wang, Y. Fu, Control approach for form accuracy of microlenses with continuous relief, Opt. Express 13 (2005) 1353–1360] via analyzing a PAC concentration distribution inside the photoresist. We analyzed the fabrication errors of the micro-optical structures which are caused by the approximate algorithm. The relief form error originating from the measurement errors of characteristics parameters of the photoresist is analyzed as well. A valid approach for a quick and accurate design of the exposure distribution is provided accordingly. As an example, a saw-tooth grating with 75 μm relief depth was designed and fabricated so as to verify the new algorithm. Our measurement results show that root mean square ( rms) value is less than 0.81 μm. The quick algorithm can satisfy the requirements of micro-optical systems for practical applications.

Rapid bending of a nonliquid crystal azobenzene polymer film and characteristics of surface relief grating

AbstractA nonliquid crystal polymer was prepared by introducing the azobenzene group into the main chain of the poly(amic acid). The polymer film can be easily prepared by a general method. The obtained film exhibits a high bending intensity and shows fast bending response and a very large bending angle (reach of 90°) at room temperature without temperature heating, which can improve the efficiency of the transformation of energy from light to mechanical energy. The surface structure of the relief grating also was investigated by atomic force microscopy. The depth of typical surface relief was approximately 65 nm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Suppression of the spectral selectivity of two-layer phase-relief diffraction structures

The method and results of studying the effect of relief depth on the attainable degree of reducing the spectral selectivity of two-layer diffraction structures based on plastics and glass. The possibilities of suppressing the spectral selectivity of double- and single-relief structures are compared.

Submicron-resolved relief formation in poled glasses and glass-metal nanocomposites

The formation of a spatial relief reproducing that of the anode as a result of the thermal poling of glasses and glass-metal nanocomposites in a strong electric field has been studied by atomic force microscopy. The anode surface patterns exhibited either a square grid or a rectangular grating with a depth of 120 nm, a strip width of 0.5 μm, and a period of 1 μm manufactured using electron-beam lithography and ion etching on the surface of an n-type single crystal silicon wafer. The relief depth formed on the surface of poled samples varied within 5–15 nm, depending on the experimental conditions. The mechanism of relief formation in this system is discussed.

Hillslope scale soil moisture variability in a steep alpine terrain

Summary In this study we analyse space–time variability of soil moisture data collected at 0–6, 0–12 and 0–20 cm depth over three hillslopes with contrasting steep relief and shallow soil depth in the Dolomites (central-eastern Italian Alps). The data have been collected during two summer seasons (2005 and 2006) with different precipitation distribution. Analysis of soil moisture data shows that different physical processes control the space–time distribution of soil moisture at the three soil depths, with a marked effect of dew on the 0–6 cm soil depth layer. The range of skewness values decreases markedly from the surface to deeper layers. More symmetric distributions, characterised by relatively low skewness, are found for mid-range soil moisture contents, while highly skewed distributions (generally with more log–normal shape) are found at dry and wet conditions. Scatter plots drawn for the whole data set and the analysis of the correlation coefficients suggest a good persistence of soil moisture with depth: the highest degree of correlation was observed between data collected at 0–12 and 0–20 cm. Examination of correlation between soil moisture fields and topographical attributes shows that, notwithstanding the steep relief and the humid conditions, terrain indices are relatively poor predictors of soil moisture spatial variability. The slope and the topographic wetness index, which are found here the best univariate spatial predictors of soil moisture, explains up to 42% of the time-averaged moisture spatial variation. A negative relationship between the soil moisture spatial mean and the corresponding spatial standard deviation is found for mean water contents exceeding 25–30%, while a transition to a positive relationship is observed with drier conditions. Overall, soil moisture variability shows the highest values at moderate moisture conditions (23–29%) and reduced values for wetter and drier conditions for all depths. A negative linear relationship between mean soil moisture content and the coefficient of variation was observed. A soil moisture dynamics model proved to successfully capture the soil moisture variability at the hillslope scale. The simulated time series of hillslope-averaged soil moisture are in good agreement with the observed ones. Moreover, the model reproduces consistently the observed relationships between soil moisture spatial mean and corresponding variability.

Variable crustal structure along the Juan de Fuca Ridge: Influence of on‐axis hot spots and absolute plate motions

Multichannel seismic and bathymetric data from the Juan de Fuca Ridge (JDFR) provide constraints on axial and ridge flank structure for the past 4–8 Ma within three spreading corridors crossing Cleft, Northern Symmetric, and Endeavour segments. Along‐axis data reveal south‐to‐north gradients in seafloor relief and presence and depth of the crustal magma lens, which indicate a warmer axial regime to the south, both on a regional scale and within individual segments. For young crust, cross‐axis lines reveal differences between segments in Moho two‐way traveltimes of 200–300 ms which indicate 0.5–1 km thicker crust at Endeavour and Cleft compared to Northern Symmetric. Moho traveltime anomalies extend beyond the 5–15 km wide axial high and coincide with distinct plateaus, 32 and 40 km wide and 200–400 m high, found at both segments. On older crust, Moho traveltimes are similar for all three segments (∼2100 ± 100 ms), indicating little difference in average crustal production prior to ∼0.6 and 0.7 Ma. The presence of broad axis‐centered bathymetric plateau with thickened crust at Cleft and Endeavour segments is attributed to recent initiation of ridge axis‐centered melt anomalies associated with the Cobb hot spot and the Heckle melt anomaly. Increased melt supply at Cleft segment upon initiation of Axial Volcano and southward propagation of Endeavour segment during the Brunhes point to rapid southward directed along‐axis channeling of melt anomalies linked to these hot spots. Preferential southward flow of the Cobb and Heckle melt anomalies and the regional‐scale south‐to‐north gradients in ridge structure along the JDFR may reflect influence of the northwesterly absolute motion of the ridge axis on subaxial melt distribution.

Fabrication of polarization grating and surface relief grating in crosslinked and non-crosslinking azopolymer by polarization holography method

Pure polarization grating without surface topology on crosslinked azopolymer film was fabricated upon exposure to an interference pattern of orthogonal linearly polarized beams from a He–Cd laser without any subsequent processing steps. The grating structure was investigated using atomic force microscopy and polarization optical microscopy. A regular spaced grating but without surface relief was observed. The grating was stable at ambient conditions and can endure repeated writing–erasing processes. The interference mode of writing beam had a significant effect on grating formation and was investigated by using the two patterns of orthogonal linearly polarized beams (polarization-modulated mode) and parallel linearly polarization beams (intensity-modulated mode). The effect of material crosslinking was also studied by comparing the surface relief depth on the grating formation process between crosslinked and non-crosslinking azopolymer films. Experiment results demonstrated that the surface relief grating was observed on non-crosslinking azopolymer film. For intensity-modulated interference mode, whatever crosslinked and non-crosslinking azopolymer films, the surface relief gratings were fabricated.

Asymmetric Polarization Conversion in Polarization Holograms with Surface Relief

We have developed holographic gratings that enable the asymmetric polarization conversion between ±1-order diffraction beams. The holographic gratings are formed by polarization holography in a poly[(methyl methacrylate)-co-(disperse yellow 7 methacrylate)] film and show both anisotropic phase and surface modulations. For an azobenzene-containing polymer film, molecular reorientation and migration are strongly dependent on the polarization state of the writing beams and can be spatially modulated. Theoretical investigation by the Jones matrix method including both modulations has shown that the polarization ellipticity of ±1-order diffraction changes as a function of relief depth. Experimental results in accordance with theoretical predictions show that the polarization gratings diffract linearly and circularly polarized beams simultaneously.

Using ellipsometry methods for depth analyzing the optical disc data layer relief structures

We studied the relief depth of the data layer formed in a glass disk by ion beam etching process with using classical ellipsometry at the constant wavelength 632.8 nm for different angles of incidence. It was found that for 0° and 90° azimuth angles, a pair of ellipsometric parameters Ψ and ∆ is sufficient to characterize the changes in light reflection for various structure depths. The depth of optical disc data layer relief structures was estimated via experimental dependences of ellipsometric parameters. The estimated data layer depths were found to be in good agreement with independent tunnelling electron microscopy measurements.

Biopolymer holographic diffraction gratings

Surface-relief diffraction gratings are holographically recorded in dextran sensitized with ammonium dichromate (DCD). DCD was exposed with single-frequency 200mW diode pumped ND-YAG laser, at 532nm. The diffraction grating profiles were analyzed by atomic force microscopy (AFM). It was found that different surface profiles could be obtained. Gratings with 330lines/mm spatial frequencies were made. Existence of higher harmonics in Fourier Transform of non-sinusoidal profiles shows that DCD is capable of recording spatial frequencies up to 1320lines/mm (four times fundamental frequency). The measured maximum relief depth of the DCD grating is 402nm.

Soil moisture monitoring on a steep hillside

AbstractIn this study, a soil monitoring system for a hillslope with steep relief and shallow soil depth was designed and installed to represent efficiently the spatial and temporal features of soil moisture. The study was conducted on a mountainous hillslope of the Sulmachun catchment (northeastern South Korea). The positions of soil moisture sensors were determined through a sequential procedure including intensive geomorphologic surveying of the study area, surface and subsurface terrain analysis, and inverse surveying. Using 26 sensors, soil moisture data from 11 locations were measured and recorded at hourly intervals over 380 h from 6 to 22 November 2003. Soil moisture response patterns were captured for a few consecutive rainfall events. The monitoring results are discussed in the context of soil moisture variations with terrain attributes. The immediate recharge and fast recession after a peak are the primary features of soil moisture in the upper zone. Stability and significant storage increase are distinct characteristics of soil moisture in the buffer zone and the flow path zone respectively. Spatial distribution of temporal soil moisture variations can be characterized in terms of recession, stability and recharge depending upon the topographic classification of a hillslope for this approach. Copyright © 2007 John Wiley & Sons, Ltd.

Relationship Between the Depth of Drilling and Residual Strain Relief in Fiber Reinforced Composite Materials

The mechanical properties of fiber are quite different from matrix in composite laminates, and parameters, such as the angle of ply, and the temperature and pressure during composite forming, would play an important role in residual stress in the composite. The residual strains between layers depend on the forming parameters and their mechanical properties. In this article, grating rosette, Moire interferometry, and step drilling-hole method are used to measure the relief strains when drilling each single laminate step by step, and find some relationship between the depth of drilling and residual strain relief in fiber reinforced composite material.

Crown condition as a function of soil, site and tree characteristics

One of the aims of this work is to describe how the target variable “tree vitality” in terms of needle loss is affected by other explanatory variables. To describe such a relationship in a realistic way, we use generalized additive mixed models (GAMMs) which allow to take spatial correlation of the data into account and in addition allow the inclusion of explanatory variables as predictors with the possibility of having non-linear effects. The GAMMs are fitted in a Bayesian framework using Markov chain Monte Carlo techniques. Data are available for two years 1988 and 1994. We select a set of best explanatory variables from a large set of variables including tree-specific variables, such as species, age, nutrients in the needles and site-specific variables such as altitude, relief type, soil depth and content of different nutrients in the top soil. In the two models for 1988 and 1994, different sets of explanatory variables were selected as best predictors. In both models, the effects of explanatory variables allowed a plausible interpretation. For example, the site-specific variables such as relief and soil depth were significant predictors, since these factors determine how well water and nutrient supply is balanced at a specific site. The selected sets of explanatory variables differed between 1988 and 1994, giving an indication of a possible change in the main causes of forest deterioration between 1988 and 1994. From the set of nutrient variables measured in the soil and in the needles, in 1988 altitude a.s.l. and magnesium supply were among the explanatory variables, in 1994 a combination of Al in the soil and the N/K-ratio (in the needles) was selected in the model. In 1988 altitude a.s.l. was among the most important predictors in the model. This is in contrast to 1994 where altitude was not selected. This may have to do with the fact that in the early phase of forest health monitoring (1988) one of the main causes of forest deterioration was magnesium deficiency. Later on this may have changed to a combination of soil acidification and nitrogen eutrophication. Thus by using an adequate model such as the GAMM, sets of explanatory variables for needle loss may be identified. By fitting two GAMMs, with different sets of “best” predictors, at two time points 1988 and 1994, we can detect changes in these sets of “best” predictors over time. This allows us to use the monitoring data with the tree vitality indicator crown condition/needle loss as a tool for forest health management, which may involve decisions about concrete counter measures like e.g. forest liming.

Sudan IV dye based poly(alkyloxymethacrylate) films for optical data storage

The polymer poly{1-[2′-methyl-4′-(2″-methylphenylazo) phenylazo]-2-(m-methacryloyloxyoctyloxy}naphthalene, where m=6, 8, 10, is synthesized by free radical addition polymerization method for holographic optical data storage. Characterization of the polymers is done by formation of the holographic grating. A study of the dependence of diffraction efficiency of the grating formed on various parameters is presented. Surface relief gratings on these polymer films are created upon exposure to argon ion laser beams at 514.5nm without any subsequent processing steps. The surface structure of the relief gratings has been investigated by atomic force microscopy. The depth of surface relief in a typical case is found to be around 40nm.

Duplication of Photoinduced Azo Polymer Surface-Relief Gratings through a Soft Lithographic Approach

In this work, a soft lithographic approach has been developed to duplicate photoinduced surface-relief-gratings (SRGs) of azo polymer films to generate the surface pattern replicas composed of different materials on various substrates. For this purpose, thin films of an epoxy-based azo polymer (BP-AZ-CA) were prepared by spin-coating, and SRGs with different structures were inscribed by exposing the films to interference patterns of Ar(+) laser beams at modest intensity (150 mW/cm(2)). Using the azo polymer films as masters, stamps of poly(dimethylsiloxane) (PDMS) were prepared by replica molding. The PDMS stamps were then used to transfer the solutions of poly(3-hexylthiophene) (P3HT), multiwalled carbon nanotube (MWNT), and BP-AZ-CA to different substrates by contact printing. Through this process, surface pattern replicas made of the functional materials were obtained. The pattern formation and quality depended on the factors such as the solution concentration, contacting time in the printing process, and printing pressure. Under the proper conditions, the printed patterns showed the same grating periods as the masters and the same relief depths as the stamps (replicas of the masters). This approach, showing some attractive characteristics such as the easiness of master preparation and the versatility of soft fabrication processes, can be applied to the fabrications of optical functional surfaces, sensors, and photonic devices.

Small relief shape variations influence spatial variability of soil chemical attributes

Soils with small variations in relief and under the same management system present differentiated spatial variabilities of their attributes. This variability is a function of soil position in the landscape, even if the relief has little expression. The aim of this work was to investigate the effects of relief shape and depth on spatial variability of soil chemical attributes in a Typic Hapludox cultivated with sugar cane at two landscape compartments. Soil samples were collected in the intercrossing points of a grid, in the traffic line, at 0-0.2 m and 0.6-0.8 m depths, comprising a set of 100 georeferenced points. The spatial variabilities of pH, P, K, Ca, Mg, cation exchange capacity and base saturation were quantified. Small relief shape variations lead to differentiated variability in soil chemical attributes as indicated by the dependence on pedoform found for chemical attributes at both 0-0.2 m and 0.6-0.8 m depths. Because of the higher variability, it is advisable to collect large number of samples in areas with concave and convex shapes. Combining relief shapes and geostatistics allows the determination of areas with different spatial variability for soil chemical attributes.