Depth Of Peaks Research Articles

Experimental Study on Near-Wall Laser-Induced Cavitation Bubble Micro-Dimple Formation on 7050 Aluminum Alloy

To investigate the feasibility and formation laws of fabricating micro-dimples induced by near-wall laser-induced cavitation bubble (LICB) on 7050 aluminum alloy. A high-speed camera and a fiber-optic hydrophone system were used to capture pulsation evolution images and acoustic signals of LICB. Meanwhile, a three-dimensional profilometer was employed to examine the contour morphology of the surface micro-dimple on the specimen. The results show that at an energy level of 500 mJ, the total pulsation period for the empty bubble is 795 μs, with individual pulsation periods of 412.5 μs, 217 μs, and 165 μs for the first, second, and third cycles, respectively, with most energy of the laser and bubble being consumed during the first evolution period. Under the synergy of the plasma shock wave and collapse shock wave, a spherical dimple with a diameter of 450 μm is formed on the sample surface with copper foil as the absorption layer. A model of micro-dimple formed by LICB impact is established. As the energy increases, the depth of the surface micro-dimple peaks at an energy of 400 mJ and then decreases. The depth of the surface micro-dimple increases with the increase in the number of impacts; the optimal technology parameters for the micro-dimple formation by LICB impact are as follows: the absorption layer is copper foil, the energy is 400 mJ, and the number of impacts is three.

An investigation into the constitutive relation of corrugated metro rail material based on nano-indentation experiment and inverse analysis

To establish the constitutive relation of corrugated rail material, rail corrugation was reproduced. The material mechanical properties of corrugation peaks and troughs were obtained by experiment. A set of dimensionless functions was proposed for the elastic modulus, hardness and yield stress at arbitrary depth of corrugation peaks and troughs. By combining the finite element model and dimensional functions, the constitutive relations were obtained at different vertical and lateral positions of corrugation. The closer the material is to the rail surface, the larger the mechanical property values. The elastic modulus and hardness of corrugated rail material at the trough surface are higher than those at the peak, while the yield stress at the peak surface is higher than the trough.

Spectral Characterization and Identification of Natural and Regenerated Leather Based on Hyperspectral Imaging System

Currently, the methods to identify leather materials have limitations, and identifying natural leather types is also relatively complex. In this research, the microstructures of four types of mammalian leathers (cattle leather, pig leather, sheep leather, and deer leather), three kinds of reptilian leathers (crocodile leather, lizard leather, and snake leather) and regenerated leather were characterized by scanning electron microscopy. The spectral curves (from 900 to 1700 nm) of these leather samples were extracted using a hyperspectral imaging system, and their spectral characteristics were analyzed. A method of leather identification by the hyperspectral imaging system combined with chemometrics was established. The results showed that the spectral curves of natural and regenerated leather differed in the number, position, and depth of the characteristic peaks, enabling the classification of regenerated leather by comparative analysis with the naked eye. The first-order derivative processing–principal component analysis–discriminant analysis model achieved a 98% correct classification rate, confirming the hyperspectral imaging system’s feasibility in the leather material identification field. We believe that his research is beneficial for the leather industry to understand the classifications scientifically, in order to protect consumer rights and further develop the leather testing industry.

Acoustical Slot Mode Sensor for the Rapid Coronaviruses Detection.

A method for the rapid detection of coronaviruses is presented on the example of the transmissible gastroenteritis virus (TGEV) directly in aqueous solutions with different conductivity. An acoustic sensor based on a slot wave in an acoustic delay line was used for the research. The addition of anti-TGEV antibodies (Abs) diluted in an aqueous solution led to a change in the depth and frequency of resonant peaks on the frequency dependence of the insertion loss of the sensor. The difference in the output parameters of the sensor before and after the biological interaction of the TGE virus in solutions with the specific antibodies allows drawing a conclusion about the presence/absence of the studied viruses in the analyzed solution. The possibility for virus detection in aqueous solutions with the conductivity of 1.9–900 μs/cm, as well as in the presence of the foreign viral particles, has been demonstrated. The analysis time did not exceed 10 min.

3D Printed Multi-material Medical Phantoms for Needle-tissue Interaction Modelling of Heterogeneous Structures

The fabrication of multi-material medical phantoms with both patient-specificity and realistic mechanical properties is of great importance for the development of surgical planning and medical training. In this work, a 3D multi-material printing system for medical phantom manufacturing was developed. Rigid and elastomeric materials are firstly combined in such application for an accurate tactile feedback. The phantom is designed with multiple layers, where silicone ink, Thermoplastic Polyurethane (TPU), and Acrylonitrile Butadiene Styrene (ABS) were chosen as printing materials for skin, soft tissue, and bone, respectively. Then, the printed phantoms were utilized for the investigation of needle-phantom interaction by needle insertion experiments. The mechanical needle-phantom interaction was characterized by skin-soft tissue interfacial puncture force, puncture depth, and number of insertion force peaks. The experiments demonstrated that the manufacturing conditions, i.e. the silicone grease ratio, interfacial thickness and the infill rate, played effective roles in regulating mechanical needle-phantom interaction. Moreover, the influences of material properties, including interfacial thickness and ultimate stress, on needle-phantom interaction were studied by finite element simulation. Also, a patient-specific forearm phantom was printed, where the anatomical features were acquired from Computed Tomography (CT) data. This study provided a potential manufacturing method for multi-material medical phantoms with tunable mechanical properties and offered guidelines for better phantom design.

Analysis of Microbial Cell Viability in a Liquid Using an Acoustic Sensor

A method was developed for the rapid analysis and evaluation of the viability of bacteriophage-infected Escherichia coli (E.coli) XL-1 directly in a conducting suspension by using a slot-mode sensor. The method is based on recording the changes in the depth and frequency of resonant absorption peaks in the frequency dependence of the insertion loss of the sensor before and after the biologic interaction of E. coli with specific bacteriophages. The possibility was shown of recording the infection of E. coli with specific bacteriophages and assessing its viability in suspensions with a conductivity of 4.5–30 μS/cm. Сontrol experiments were carried out with non-specific interactions of E. coli cells with bacteriophages, in which no changes in the sensor variables were observed. The optimal informational variable for estimating the number of viable cells was the degree of change in the depth of the resonant peaks in the frequency dependence of the insertion loss of the sensor. The limit of cell detection was ∼102–103 cells mL–1, with an analysis time of about 5 min. An additional advantage of the sensor was the availability of a removable liquid container, which allows one to use it repeatedly and to facilitate the cleaning of the container from spent samples. The results are promising for the detection of bacteria and assessment of their viability in solutions with conductivity in the range 4.5–30 µS/cm.

Sensor based on the slot acoustic wave for the non-contact analysis of the bacterial cells – Antibody binding in the conducting suspensions

The possibilities of using the acoustic sensor based on the slot mode in the delay line with a shear horizontal acoustic wave of zero order for the contactless analysis of the bacterial cells-antibody binding in the conducting suspensions were investigated. In this sensor, the suspension container, the bottom of which was made of the lithium niobate plate, was located above the delay line with the given width of the gap. The excitation of the slot mode in such a structure led to the appearance of the sharp resonant peaks on the frequency dependence of the insertion loss of the delay line. It has been established that the specific interaction of the bacterial cells with the antibodies in the suspensions with the different electrical conductivity leads to a change in the depth and frequency of the resonant peaks in the frequency dependence of the insertion loss of the sensor. The dependences of the changes in the depth and frequency of the resonant peaks on the conductivity of the buffer solution with the different cell concentrations were determined for the specific interaction of the “bacterial cells – antibodies”. The possibility of the use of the slot mode in the sensor to analyze the bacterial cells with the help of the antibodies in the suspensions with an initial conductivity of 5–20 μS/cm is shown. The advantage of the novel sensor is that its design allows the easy and high-quality cleaning the container from the spent cell suspension separately from the delay line.

Research on tunable phase shift induced by piezoelectric transducer in linearly chirped fiber Bragg grating with the V-I transmission matrix formalism

In this study, the V-I transmission matrix (V-I TM) is proposed to analyze the tunable single phase shift (SPS) and multiple phase shifts (MPS) inserted in a linearly chirped fiber Bragg grating (LCFBG). According to the simulation results, the peaks appear on the transmission spectrum, when the phase shifts are induced in the LCFBG. With the increase of the phase shift, the center wavelength of the peak moves toward long wavelength region. A remarkable degree of bilateral symmetry can be found as characteristic of the depth of peaks. The maximum depth caused by inserted π-shift is the symmetric axis. Moreover, when MPS are inserted simultaneously, the appeared peaks are independent and the variation tendency of each peak is the same with that caused by SPS. The experiment of phase shift induced by a piezoelectric transducer (PZT) verifies the correctness of the simulation, and a narrow bandwidth of 0.028nm is acquired.

Hyperspectral analysis of clay minerals

Abstract. A study was carried out by collecting soil samples from parts of Gwalior and Shivpuri district, Madhya Pradesh in order to assess the dominant clay mineral of these soils using hyperspectral data, as 0.4 to 2.5 μm spectral range provides abundant and unique information about many important earth-surface minerals. Understanding the spectral response along with the soil chemical properties can provide important clues for retrieval of mineralogical soil properties. The soil samples were collected based on stratified random sampling approach and dominant clay minerals were identified through XRD analysis. The absorption feature parameters like depth, width, area and asymmetry of the absorption peaks were derived from spectral profile of soil samples through DISPEC tool. The derived absorption feature parameters were used as inputs for modelling the dominant soil clay mineral present in the unknown samples using Random forest approach which resulted in kappa accuracy of 0.795. Besides, an attempt was made to classify the Hyperion data using Spectral Angle Mapper (SAM) algorithm with an overall accuracy of 68.43 %. Results showed that kaolinite was the dominant mineral present in the soils followed by montmorillonite in the study area.

Effects of Annealing on Thermoluminescence Peak Positions and Trap Depths of Synthetic and Natural Quartz by Means of the Various Heating Rate Method

Some environmental and experimental variables such as annealing process alter the structure of glow curves of some thermoluminescence materials. We investigate the effects of annnealing on thermoluminescence peaks of synthetic and natural quartz at different heating rates. The experimental results show that the peak temperatures of glow peaks in annealed samples shift to higher temperature sides. The amount of shifting is higher for low temperature peaks than high temperature peaks. The trap depths of annealed and unannealed samples of both synthetic and natural quartz are also obtained by various heating rate methods. It is noted that the annealing process affects the trap depth of all glow peaks and the trap depth increases after the annealing process.

Response to Interpreting the ash trend within ombrotrophic bog profiles: atmospheric dust depositions vs. mineralization processes. The Etang de la Gruère case study

In ‘Interpreting the ash trend within ombrotrophic bog profiles: atmospheric dust depositions vs. mineralization processes. The Etang de la Gruere case study’, Zaccone et al. (2011a) question our interpretation of enhanced ash contents in depth profiles of ombrotrophic bogs. We see them as an indication for C-loss through peat decay (Leifeld et al. 2011). We highly appreciate the work by Claudio Zaccone, William Shotyk and co-authors on peatlands, including their discussion of methods and their limitations. The approach described in Leifeld et al. (2011) has the potential to overcome some limitations of other methods to estimate C-loss from disturbed peatlands but needs to be carefully evaluated. The criticism of Zaccone et al. (2011a) relates to one (EGr) of the four different bogs discussed in our study. EGr is a rather small bog (5 ha). Therefore, the concerns raised in this single case may not be generalized. In our study, EGr served as a reference site and its ash peak has been attributed mainly to human disturbance but less to changing patterns in atmospheric deposition or drainage. Zaccone et al. (2011a) challenge this assumption and raise three points of concern, (1) sampling methodology, (2) normalization of ash peaks to depth, and (3) discussion and interpretation of ash peaks. We reply to each of them.

Environmental factors controlling the vertical distribution of phytoplankton in lakes

Observations from single lake and experimental studies predict that vertical habitat heterogeneity in lakes can influence phytoplankton community structure. We examined the nature of water column physical habitat structure (light penetration, thermocline depth and shape and relative thermal resistance to mixing), and in turn, how these structures influenced the distribution of bulk chlorophyll a and the biomass of several major phytoplankton groups across 45 lakes in eastern Canada, within two lake districts which varied in watershed geology and water chemistry. Across all lakes, more pronounced temperature gradients favoured the distribution of bulk phytoplankton into more defined layers. The depth at which peak chlorophyll a was observed was affected by temperature heterogeneity and environmental factors related to light penetration. Peak depths and vertical heterogeneity of the major phytoplankton groups were differentially related to epilimnetic water colour and total phosphorus concentration across all lakes. Further insight was gained by comparing the physical structure and phytoplankton responses in the two regions. Lakes from the Laurentians Region had less wind exposure, shallower thermoclines, but greater vertical temperature variability than in the Eastern Townships Region. As a result, total and major phytoplankton group biomass showed more heterogeneous distributions in the Laurentians. The depth of peaks in total biomass and for the major phytoplankton groups was similar in both regions; the exception being a deeper chlorophyte maximum in the ETR, suggesting that there may be important differences between regions in the taxonomic composition of this group.

Observations of the Transition Layer

Abstract The transition layer is the poorly understood interface between the stratified, weakly turbulent interior and the strongly turbulent surface mixed layer. The transition layer displays elevated thermohaline variance compared to the interior and maxima in current shear, vertical stratification, and potential vorticity. A database of 91 916 km or 25 426 vertical profiles of temperature and salinity from SeaSoar, a towed vehicle, is used to define the transition layer thickness. Acoustic Doppler current measurements are also used, when available. Statistics of the transition layer thickness are compared for 232 straight SeaSoar sections, which range in length from 65 to 1129 km with typical horizontal resolution of ∼4 km and vertical resolution of 8 m. Transition layer thicknesses are calculated in three groups from 1) vertical displacements of the mixed layer base and of interior isopycnals into the mixed layer; 2) the depths below the mixed layer depth of peaks in shear, stratification, and potential vorticity and their widths; and 3) the depths below or above the mixed layer depth of extrema in thermohaline variance, density ratio, and isopycnal slope. From each SeaSoar section, the authors compile either a single value or a median value for each of the above measures. Each definition yields a median transition layer thickness from 8 to 24 m below the mixed layer depth. The only exception is the median depth of the maximum isopycnal slope, which is 37 m above the mixed layer base, but its mode is 15–25 m above the mixed layer base. Although the depths of the stratification, shear, and potential vorticity peaks below the mixed layer are not correlated with the mixed layer depth, the widths of the shear and potential vorticity peaks are. Transition layer thicknesses from displacements and the full width at half maximum of the shear and potential vorticity peak give transition layer thicknesses from 0.11× to 0.22× the mean depth of the mixed layer. From individual profiles, the depth of the shear peak below the stratification peak has a median value of 6 m, which shows that momentum fluxes penetrate farther than buoyancy fluxes. A typical horizontal scale of 5–10 km for the transition layer comes from the product of the isopycnal slope and a transition layer thickness suggesting the importance of submesoscale processes in forming the transition layer. Two possible parameterizations for transition layer thickness are 1) a constant of 11–24 m below the mixed layer depth as found for the shear, stratification, potential vorticity, and thermohaline variance maxima and the density ratio extrema; and 2) a linear function of mixed layer depth as found for isopycnal displacements and the widths of the shear and potential vorticity peaks.

210Pb and 137Cs dating methods in lakes: A retrospective study

210Pb has been used for more than two decades to provide the geochronology of annually deposited sediments and to construct pollution histories. Evidence from some lakes suggests that this radionuclide may be adequately mobile to compromise dating reliability. This study provides one test of that possibility by comparing recent measurements of 210Pb and trace metals to ones carried out more than 20 yrs in the past. 137Cs dating is used to confirm sediment accumulation rates in the recent cores. In the three Connecticut, USA, lakes studied, sediment accumulation rates changed abruptly to higher values between 40-50 yrs ago (increasing by factors of 2.2, 2.9, and 3.0). In all three lakes, rates calculated from 210Pb distributions both above and below this horizon agreed, within measurement uncertainty, in recent and older cores. Furthermore, when the older data were corrected for 20 yrs of burial, the changes in slope in 210Pb distributions occurred at the same depth in each pair of cores. The depth of sharp peaks in concentrations of trace metals also matched. In general, this evidence supports the idea that sediments in these lakes have simply been buried, without significant diagenetic remobilization of 210Pb and trace metals . Nevertheless, some important differences were also observed. For two of the three lakes, there was a significant difference in average sediment accumulation rate during the past 33 yrs as calculated from 137Cs and 210Pb in the recent cores. Most potential causes for this difference can be ruled out, and it appears that one of the two nuclides is remobilized compared to the other. There were also significant differences in the total inventories of both 210Pb and trace metals (both up to 2 ×) between recent and older cores in some cases. This may be due to dissimilar sediment focusing, since it is not known for certain whether the new cores were collected at exactly the same sites as in the past.

The effect of anisotropy in Co/sub 66/Fe/sub 4/Ni/sub 1/B/sub 14/Si/sub 15/ ribbon on the transverse incremental permeability and magnetoimpedance

The transverse incremental permeability and magneto-impedance effects in amorphous Co/sub 66/Fe/sub 4/Ni/sub 1/B/sub 14/Si/sub 15/ ribbons treated with various annealing and etching conditions have been investigated in conjunction with their magnetic anisotropy. The shape and the depth of double peaks in magneto-impedance ratio (MIR) and transverse permeability ratio (TPR) curves show the existence of the uniaxial magnetic anisotropy. The direction of magnetic anisotropy in samples annealed under magnetic field was induced parallel to their magnetic field. The direction of magnetic anisotropy in samples annealed without the magnetic field has changed ribbon to width direction. The surface etching of an as-quenched sample helps to orient the magnetic anisotropy to the ribbon axis. The maximum values of MIR and TPR depend on the magnetic softness rather than the direction of magnetic anisotropy. However, the shapes of MIR and TPR curves strongly depend on their uniaxial magnetic anisotropy.

Competitive Oxidation During Buried Oxide Formation Using Separation by Plasma Implantation of Oxygen (Spimox)

AbstractWe have recently demonstrated a new implantation technique called SPIMOX (separation by plasma implantation of oxygen) to synthesize silicon-on-insulator structures using plasma immersion ion implantation (PIII) process. the implantation is performed by applying a large negative bias to a Si wafer immersed in an oxygen plasma created by an ECR source. Since the technique has no mass analysis, coexistence of O+ and O2+ ions in oxygen plasma can cause a non-Gaussian profile of the as-implanted oxygen distribution. We observed that during post-implantation annealing, the ripening process of the oxide precipitates depends on depth and concentration of the oxygen peaks. IN addition, implanted oxygen can migrate towards the Si surface during annealing, preventing a continuous buried oxide layer formation. IN this paper, we report our observation on the effect of the implantation profile on the competitions between internal oxidation at different depths and between internal and surface oxidation processes. With an additional He implantation, we demonstrate that the nucleation of oxide precipitation can be enhanced.