Channel Position Research Articles

Cyclic channel-shoal dynamics at the Ameland inlet: the impact on waves, tides, and sediment transport

Ebb-tidal deltas are shallow features seaward of tidal inlets, acting as a wave filter for the nearby barrier island and a source of sediment for the landward tidal basin. On many ebb-tidal deltas, channels rotate and shoals periodically attach to the downdrift island. This cyclic behavior can also include an alternation between one- and two-channel inlet configurations. The effect of the long-term (> years) cyclic behavior on the short-term patterns of waves, tidal currents, and sediment transport is unknown. Here, we use Delft3D/SWAN models to simulate the Dutch Ameland tidal inlet during four phases of the cycle to show that many of the physical processes on the ebb-tidal delta and in the entire tidal system are affected by the cyclic evolution of channels and shoals. In particular, the periodic variations in the channel positions appear to significantly influence the tidal asymmetry in the inlet and mean flow characteristics. As a result, the net sediment exchange between basin and sea is cyclic and follows the periodicity of the one- and two-channel inlet configuration. Moreover, we find that the wave energy dissipation on the ebb-tidal delta is enhanced by a shallow shoal or an updrift-oriented ebb-channel, which shields the coast from the incoming waves. Our results demonstrate how the cyclic channel-shoal dynamics at natural tidal inlets is likely to affect the safety functions of the ebb-tidal deltas, varying the offshore wave energy dissipation as well as adjusting the sediment pathways on the ebb-tidal delta.

Decadal-scale morphological adjustment of a lowland tropical river

Compared with temperate regions, much less is known about the dynamics of tropical river systems. Tropical rivers are typically characterised by pronounced seasonal changes in precipitation, large sediment loads and high rates of lateral channel migration across often very low-gradient and densely populated floodplains. Understanding the controls on channel migration or change is integral to our ability to fully predict and build resilience against flood risk and wider river-related hazards. Here, we analyse channel and confluence migration over the last ~40years along a ~85km reach of the Cagayan River and one of its tributaries, the Pinacanauan de Ilagan (Luzon, Philippines) using optical satellite imagery captured during this period. Combining this with spatial variations in channel pattern, valley width and new bed material grain size data, we demonstrate that sediment transport and deposition are key drivers of the observed tropical channel morphodynamics in this region. The high sediment supply generated in the catchment headwaters (by mass-wasting of hillslopes triggered especially in typhoons) results in high aggradation rates and channel widening on the lower gradient alluvial plain. We suggest that this aggradation enhances local confluence and lateral channel migration rates, which can reach >300m per decade, and that lateral migration rates of tropical rivers are typically greater than those of temperate rivers. Channel morphodynamics have implications for how to best manage these types of tropical river systems, where hard bank protection structures may result in a complex geomorphic response and flood risk mapping may need to include assessment of sensitivity to varying channel position and topography.

Numerical model of aqueous humor drainage: effects of collector channel position

Glaucoma is a progressive and a degenerative eye disease that gradually deteriorates the vision. The origin of glaucoma is still under debate. Recent studies report that 50% of the aqueous humor outflow resistance resides on collector channels and Schlemm’s canal (SC). This paper provides a descriptive analysis of the aqueous humor outflow through the anterior chamber, the trabecular meshwork (TM) and the SC. The aim of this work is to determine the influence of the collector channels position on the intraocular pressure (IOP) and its contribution to the development of glaucoma. Pressure and wall shear stress distributions are presented for four cases. The first case has an arrangement of collector channels according to micro CT (Gong and Francis, 2014). The remaining cases have an symmetrical distribution; case 2 has all open quadrants (AOQ), cases 3 have three quadrants completely open and just one quadrant semi closed (SCQ), and finally cases 4 consider that a quadrant is completely closed (CQ). Symmetrical and micro CT cases have 29 collector channels. The results show that the position and the opening of the collector channels have a strong influence on the IOP.

Three-Dimensional and Chemical Mapping of Intracellular Signaling Nanodomains in Health and Disease with Enhanced Expansion Microscopy.

Nanodomains are intracellular foci which transduce signals between major cellular compartments. One of the most ubiquitous signal transducers, the ryanodine receptor (RyR) calcium channel, is tightly clustered within these nanodomains. Super-resolution microscopy has previously been used to visualize RyR clusters near the cell surface. A majority of nanodomains located deeper within cells have remained unresolved due to limited imaging depths and axial resolution of these modalities. A series of enhancements made to expansion microscopy allowed individual RyRs to be resolved within planar nanodomains at the cell periphery and the curved nanodomains located deeper within the interiors of cardiomyocytes. With a resolution of ∼ 15 nm, we localized both the position of RyRs and their individual phosphorylation for the residue Ser2808. With a three-dimensional imaging protocol, we observed disturbances to the RyR arrays in the nanometer scale which accompanied right-heart failure caused by pulmonary hypertension. The disease coincided with a distinct gradient of RyR hyperphosphorylation from the edge of the nanodomain toward the center, not seen in healthy cells. This spatial profile appeared to contrast distinctly from that sustained by the cells during acute, physiological hyperphosphorylation when they were stimulated with a β-adrenergic agonist. Simulations of RyR arrays based on the experimentally determined channel positions and phosphorylation signatures showed how the nanoscale dispersal of the RyRs during pathology diminishes its intrinsic likelihood to ignite a calcium signal. It also revealed that the natural topography of RyR phosphorylation could offset potential heterogeneity in nanodomain excitability which may arise from such RyR reorganization.

Effect of cooling channel position on heat transfer characteristics and thermoelectric performance of air-cooled PV/T system

An investigation on the effect of cooling channel position on heat transfer characteristics and thermoelectric performance of air-cooled PV/T systems has been conducted numerically. Two design positions, cooling channels above PV panel (case1) and below PV panel (case2), were considered. It is found that the effect of internal radiation in the cooling channel on the system performance is greater for case1 in comparison to case2, while an opposite behavior is presented for the cooling effect on PV panels. Except for the effect of air inlet temperature, the magnitude and variation trend of the convective Nusselt number on PV panels are almost the same for two case systems. A maximum total exergy efficiency is obtained at the air inlet temperature of 298.15 K for case1 system and 295.65 K for case2 system. From the perspective of the amount of supplied energy, the case1 system is preferred. Detailed analysis focusing on the quality of energy should be carried out to determine the merits of case1 and case2 systems.

Development of food orientation of agricultural production

The article examines the process of strengthening the food orientation of agriculture, as well as the possibilities of developing production and increasing the export potential of horticulture, viticulture and vegetable growing in the Namangan region of Uzbekistan. Researchers point out difficulties in product sales. Wholesale buyers of the domestic market and large processors purchase products at unreasonably low prices, due to their monopoly position and insufficient development of wholesale trade channels. In addition, the production infrastructure is mainly funded by the state, there is a market infrastructure for selling products of the industry, there is a steady demand for the products of the industry in the domestic and foreign markets. It should be noted that both in the country as a whole and in the Namangan region the technical and technological lag of agriculture has not yet been overcome.

A Simple Microfluidic Device for Generating Solute Concentration Gradients

Abstract The major focus of the present study is to develop a simple microfluidic device to generate a stable concentration gradient of solute in a flow-free regime. The microfluidic device is prepared using photolithography and soft lithography techniques. The device consists of two reservoirs for two different fluids in which one of the fluids contains the solute component. The reservoirs are connected through the main channel in which solute concentration gradient is generated by diffusion of solute molecules. Further, the mid position of this main channel is connected to a vertical channel. Here, we show a generation of linear solute gradient sustainable up to 2 h. This novel technique of generating solute gradient can be used in future to study phoretic motion, chemotaxis or any other phenomenon where maintaining steady gradient plays an important role

Thermo-fluid Topology Optimization and Experimental Study of Conformal Cooling Channels for 3D Printed Plastic Injection Molds

Abstract With the advent of additive manufacturing, innovative design methods, such as network-based techniques, and structural topology optimization have been used to generate complex and highly efficient cooling systems in recent years. However, methods that incorporate coupled thermal and fluid analysis remain scarce. In this paper, a coupled thermal-fluid topology optimization algorithm is introduced for the design of conformal cooling channels. The problem is formulated based on a coupling of Navier- Stokes equations and convection-diffusion equation. The problem is solved by gradient-based optimization after analytical sensitivity derived using adjoint method. With this method, the channel position problem is replaced to a material distribution problem. The material distribution directly depends on the effect of flow resistance, heat conduction, natural and forced convection. The algorithm leads to a two-dimensional conceptual design having optimal heat transfer and balanced flow, which is further transformed into three-dimensional cooling channel design. Here, a comprehensive study is presented, starting from design, simulation, 3D printing process and experimental testing of an injection mold with conformal cooling channels in industrial production environment. A traditional mold model is provided by an industrial collaborator. To enhance the overall thermo-fluid performance of the mold and improve final product quality, a redesign of this mold core is done with conformal cooling channels inside. The final design is 3D printed in pre-alloyed tool-steel powder Maraging Steel using Truprint 3000 metal 3D printing machine. The printed core required some heat treatment and finishing processes and added features to be incorporated to make it production ready. Once all the preparation was complete, the core was tested experimentally in a multicavity injection molding machine in real industrial environment at our industrial partner’s production facility. This paper describes all the steps starting from design, analysis, die 3D printing and finally ending at final experimental testing, as well as recommendations for tool designer and injection molding industry to implement additive manufacturing for their benefit. This paper is not just focused on a specific aspect such as design, simulation or manufacturing, but rather a comprehensive paper presenting a case study on implementation of topology optimization and additive manufacturing in real life industrial production scenario.

Avulsion Dynamics in a River with Alternating Bedrock and Alluvial Reaches, Huron River, Northern Ohio (USA)

The Huron River consists of alternating bedrock reaches and alluvial reaches. Analysis of historical aerial photography from 1950-2015 reveals six major channel avulsion events in the 8-km study area. These avulsions occurred in the alluvial reaches but were strongly influenced by the properties of the upstream bedrock reach (“inherited characteristics”). The bedrock reaches aligned with the azimuth of joint sets in the underlying bedrock. One inherited characteristic in the alluvial reach downstream is that the avulsion channels diverged only slightly from the orientation of the upstream bedrock channel (range 2 ° - 38 °, mean and standard deviation 12.1 ° ± 13.7 °). A second inherited characteristic is that avulsion channels were initiated from short distances downstream after exiting the upstream bedrock channel reach (range 62 - 266 m, mean and standard deviation 143.7 ± 71.0 m), which is a fraction of the meander wavelength (1.2 km). Field evidence shows that some avulsion channel sites were re-occupied episodically. In addition, two properties were necessary for channel avulsions: 1) avulsion events were triggered by channel-forming hydrologic events (5-year recurrence interval flows), but not every channel-forming hydrologic event resulted in an avulsion, and 2) channel sinuosity (P) increased to 1.72 - 1.77 prior to an avulsion then decreased to 1.65 - 1.70 following an avulsion, suggesting that P ≥ 1.72 is the “critical sinuosity” or triggering value for avulsions on the Huron River. In summary, for this river consisting of alternating bedrock and alluvial reaches, the bedrock reaches impose certain parameters on downstream alluvial reaches (including sediment supply, channel direction and avulsion channel position downstream after exiting a bedrock reach) while adjustments in sinuosity and sediment storage occur in the alluvial reaches.

Quantitative Determination of Urine Glucose: Combination of Laminar Flow in Microfluidic Chip with SERS Probe Technique

A surface-enhanced Raman scattering(SERS) sensing approach for urine glucose was developed based on the laminar flow technology in a cross-type microfluidic chip with SERS probes, 4-mercaptophenylboronic acid (MPBA) functionalized Ag nanoparticles. MPBA as the glucose receptor can identify and bind up with glucose at a molar ratio of 2:1, which can cause the aggregation of SERS probes at a certain position of the chip channel and further enhance the SERS signal of MPBA significantly. Thus, the quantitative SERS detection of glucose was achieved indirectly. No sample pretreatment and separation were needed in this method since the SERS detection was achieved in the gradient diffusion and molecular recognition processes between urine glucose and SERS probe in the laminar flow, which simplified the sample treatment procedures, saved detection time and made it feasible for clinic applications. This method shows a good linear relationship within human body’s normal physiological range and has high sensitivity and selectivity. The lowest detection concentration can reach 1.0 mg/dL.

Microencapsulation of beta cells in collagen micro-disks via circular pneumatically actuated soft micro-mold (cPASMO) device

The artificial pancreas provides a method for automatically managing insulin concentrations in patients with Type I diabetes. One strategy for fabricating an artificial pancreas is the encapsulation of beta cells in a collagen matrix, which can provide mechanical support. In addition, encapsulation of beta cells in small volumes and with high surface areas allows them to quickly sense glucose and secrete insulin for regulation. Currently, there is no such fabrication technique of encapsulating beta cells in a collagen matrix, due to their inherent fragility. Herein, we develop a novel technique called circular Pneumatic Actuated Soft Micromold (cPASMO) to produce collagen microdisks for encapsulating beta cells. cPASMO consists of a particle template, pneumatic channel, and buffer layer to control deformation. The actuation mechanism is simply to deform the template by increasing the inner pressure inside the channel. This deformation in the template generates a gap between the collagen microdisks and mold that can extract the collagen microdisks via buoyancy force. Thus, they can be released from their templates without damage. The position of the air channel determines the uniformity of the template deformation that leads to the high collagen microdisk extraction rate. Compared to the previous design (i.e., linear air channel), the extraction rate is four times faster. We demonstrated that beta cells encapsulated in collagen micro disks by a cPASMO device exhibit a biological function of rapidly sensing glucose and secreting insulin for regulation. The concentration of the secreted insulin from the encapsulated beta cells is three to six times higher than that of suspended cells. Also, smaller collagen micro disks release higher concentrations of insulin than those that are larger because the larger spaces between beta cells can degrade cellular communication. These breakthroughs in producing collagen microdisks will push the boundaries of treatment for Type I diabetic patients.

Optimized channel allocation scheme for jointly reducing four-wave mixing and Raman scattering in the DWDM-QKD system.

Conducting quantum key distribution (QKD) through existing optical fibers together with conventional communication signals is a viable way to expand its practical application, but weak quantum signals can be severely disrupted by co-propagating classical signals. In this paper, the suppression of four-wave mixing (FWM) noise and Raman noise is considered simultaneously for the first time, to the best of our knowledge, and the joint optimized channel allocation (JOCA) scheme is proposed. In the JOCA scheme, the quantum channels and classical channels are interleaved with each other to avoid FWM noise and optimal quantum channel positions are chosen in variable conditions according to the Raman scattering spectrum. Experimental measurements of the noise photons show that the JOCA scheme can effectively reduce the impairments on quantum signals compared with the single-target schemes. Additionally, simulation results verify that the JOCA scheme can increase the secure key generation rate and transmission distance, and that it also enables the DWDM-QKD system to tolerate higher-power classical signals and more classical channels, which improve the compatibility with a high-capacity communication system.

Response of azimuthal acoustic logging to the fluid-filled strip channel behind a casing pipe

One of the most important applications of acoustic well logging is to evaluate the cementation quality in the casing hole; such evaluation is in fact a physical question of detecting the position of the fluid-filled strip channel that is actually distributed in a limited azimuthal and axial zone behind the casing pipe. Currently, a common detection method is to measure the amplitude of the casing wave (ACW) in different azimuths and then reverse the position of the strip channel. Thus, in this paper, a 3D finite-difference algorithm is developed to study the azimuthal distribution of ACW caused by the strip channel. The simulation results show that ACW is affected by many parameters such as the radial position of azimuthal receivers and the azimuthal angle of the strip channel. More importantly, the product of the inner diameter of the casing pipe and the central frequency of the source will determine the azimuthal distribution of ACW: ACW reaches the maximum at the opposite azimuth of the strip channel when the product is below the threshold value, and it reaches the maximum at the central azimuth of the strip channel when the product is above the threshold value.

Mapping tidal channel dynamics in the Sundarbans, Bangladesh, between 1974 and 2017, and implications for the sustainability of the Sundarbans mangrove forest.

This study presents the spatial and temporal dynamics of tidal channels in the Bangladesh Sundarbans. Parts of the Passur River system were considered for this investigation. Tidal channel bank layers were extracted from aerial photographs from 1974 and 2011 and a Sentinel-2 image from 2017. On-screen digitizing of a tidal channel was undertaken to create the tidal channel layers, and special care was taken during digitization to obtain more accurate results. Layers were overlaid together so that the tidal channel position could be seen for each date. Tidal channel positions were highlighted to infer the erosion/accretion sectors along the channel, and the tidal channel dynamics were calculated. Remote sensing and Geographic Information System (GIS) platforms were used to analyse, interpret and visualize data on accretion and erosion, as well as the locations of the tidal channel bank over different years. The results revealed that erosion was severe in the larger channels, whereas accretion was dominant in the smaller channels. These erosion and accretion processes played an active role in the displacement of tidal channel banks during the period under investigation. Displacement of the tidal channel bank has had a profound impact on the Sundarbans mangrove ecosystem, and continued erosion and accretion processes are of concern for the future sustainability of biodiversity in the Sundarbans. While in the short term, these changes may not have much impact; over decades, the dynamics of tidal channels may significantly contribute to the imbalance of fauna and flora in the Sundarbans.

P30 - Does the working channel position have a role on the efficacy of Ho:YAG Laser lithotripsy? results from a laboratory test

P30 - Does the working channel position have a role on the efficacy of Ho:YAG Laser lithotripsy? results from a laboratory test

Posterior Percutaneous Endoscopic Cervical Diskectomy: A Single-Center Experience of 252 Cases

Posterior percutaneous endoscopic cervical foraminotomy and diskectomy has remarkably evolved with successful results. Although percutaneous endoscopic cervical diskectomy (PECD) has gained popularity, the risk of surgical failure may be a major obstacle to performing PECD. We analyzed unsuccessful cases requiring reoperation. The objective of this article was to find common causes of surgical failure and elucidate the limitations of the conventional PECD technique. Surgery-related complications were reviewed from the initial 252 cases of a single surgeon. The patients had cervical disk herniation or radiculopathy and underwent percutaneous endoscopic surgical management. We investigated clinical outcomes and complications. A retrospective review was performed on all patients who had undergone PECD between April 2013 and April 2016. Unsuccessful PECD was defined as a case requiring reoperation within 6 weeks after primary surgery. Chart review was done, and pre-, intra-, and postoperative radiographic reviews were performed. All unsuccessful PECD cases were classified according to the type of herniated disc, location of herniation, extruded disk migration, working channel position, and intra- and postoperative findings. The mean operative time was 89.4 minutes (range, 60-180 minutes). The mean intraoperative blood loss was 20.3 mL (range, 10-800 mL). Cerebrospinal fluid leakage occurred in 1 patient and healed well. The follow-up period ranged from 24 to 60 months. The mean score on the visual analog scale improved from 8.67 ± 1.30 preoperatively to 7.83 ± 1.40 at 1 month postoperatively to 1.67±1.30 at the final follow-up (P < 0.05), with a recovery rate of 67.9% ± 21.2%. Surgeons should be aware of the specific complications for the PECD approach.

MULTI-BRAIN NETWORK ACROSS CONSUMERS’ RIGHT INFERIOR FRONTAL GYRUS PREDICTS THEIR ATTITUDES TOWARD ADVERTISING

Introduction How to evaluate quality of advertising? Previous behavioral studies have mainly focused on subjective reports of survey and interview containing social and cognitive bias, or objective data of sell changes suffering huge temporal and monetary cost. Recently, increasing researchers have proposed that techniques of neuro-imaging could provide an objective and effective way to examine cognitive neural mechanisms underlying consumer behavior (referred to as consumer neuroscience) (Karmarkar & Yoon, 2016), and several studies have measured consumer's brain responses to advertising and movie trailer in both single- and two-brain frames (Barnett & Cerf, 2017; Venkatraman et al., 2015). However, still little is known about cognitive neural mechanisms underlying comprehension of advertising. Functional near-infrared spectroscopy (fNIRS) is a non-invasive technique of brain-imaging measuring changes in the hemodynamic properties of human brain. Compared with fMRI and EEG, fNIRS is portable, has few physical constraints on participants with reasonable spatial and temporal resolution, and is tolerant to electromagnetic noise and motion artifact. Therefore, fNIRS is a suitable tool for research of human behavior in daily-life contexts (Liu et al., in press), which is a trends in neuroimaging (Hasson & Honey, 2012) and consumer neuroscience as weill. Methods To examine the neural responses to different quality of advertisings, in the present study we measured 14 undergraduate students' frontal activations while watching 20 advertisings in Study 1 and listening 30 music demos in Study 2 using a portable fNIRS device, and analyzed interpersonal neural network across all participants based on graph theory. Figure 1 shows positions of the fNIRS channels. Positions of the fNIRS channels were measured by a 3D magnetic digitizer. In a pilot study, another group of participants were recruited to score 30 advertisings from three dimensions: degree of liking, degree of willing to pay (WTP), and degree of understanding, and finally top-10 and bottom-10 scored adverting were remained for the final experiment in Study 1. Concerning the music demos used in Study 2, we selected the top-15 and bottow-15 ranking music in the ‘Billboard 2014 hot 100’. During the experiment, participants were asked to score their degree of liking and WTP to the advertising or the music immediately after each stimulus was displayed. After the experiment, they were also instructed to score and report their understanding on each advertising or music. Results and Discussion In Study 1, the intra-brain activations revealed higher medial prefrontal cortex (mPFC) activation when participants watched low-scored advertisings than watched high-scored ones (Fig. 2), and the mPFC activations showed a positive relationship with participants’ understanding on the meaning of the advertisings. This result only suggests that low-scored advertisings were relatively hard for participants to understand the intentions of the adverting, requiring more cognitive resources of mentalizing (Lieberman, 2007). Importantly, when we considered all participants' brains as a network, and then calculated the interpersonal neural connectivity (INS) across the network (defined as the number of participant pairs who showed significant positive inter-brain neural synchronization across them indicating shared understanding) (Hasson et al., 2012), only the network connectivity in the right inferior frontal gyrus (IFG) had significantly positive relationships with participants' scores of attitude towards the advertisings (defined as mean of the scores of liking and WTP) (Fig. 3). Study 2 confirmed the result showing significantly positive relationship between the network connectivity across all participants' brains and their scores of attitude towards the song demos. More importantly, the network connectivity in the right IFG of the small group of participants also significantly predicted the public's attitude towards the songs assessed by the rating scores on Douban website (Fig. 4). Conclusion The right IFG is a core area of mirror neuron system and is closely associated with empathy (Lamm et al., 2007). Thus, the present results suggest that high-scored advertisings may activate consumer's empathic response to simulate and experience their contents and intentions. And the network connectivity across consumers' brains in the right IFG may be a critical index evaluating quality of experiential advertisings. Practically, advertising should invite consumers to experience their products, and then could convey information and emotion more effectively.

Structure of Channel Management and Agency Theory: Relationship Marketing Approach for Fast Moving Consumer Goods (FMCG) Business

This article aimed at identifying, describing, and obtaining deep understanding about channel management to reveal the characteristics of relationship-marketing theory. As such, it utilizes the agency theoretical perspective which is occasionally used in prior relationship-marketing research. The research uses qualitative method based on phenomenology theoretical-design and constructivism philosophy to observed fast-moving consumer goods business phenomenon within transactional buying-selling process in the channel management structure. Such design will be applied through the mechanism of distribution channels in traditional trade. The result identifies three positions of distribution channels within the agency theory perspective: (1) relationship between principal, distributor and promotional agencies in an efficient contract position, (2) relationship between distributor, wholesaler and retailer in the position of the realized outcomes, and (3) relationship between wholesaler, retailer and the end-users in a pay-offs position. The findings viewed as a constructive way in describing the re-design model structure of channel management from the agency theoretical perspective. As such, the research revealed three characteristics of relationship marketing; exclusive contract, direct competitive, and temporary contract approach. This research implies that the agency theoretical perspective will emerge as a new and prosperous theoretical perspective in the field of relationship marketing research in the future. It might be argued that managers in applying any relationship marketing approach are advised to stay focused on improving the quality of relationships among the partners covered by each channel-group. Further, it is expected that future research in the field of marketing management, particularly on relationship-marketing research, to utilize the agency theory as their theoretical strands.

Crystal chemistry of K-rich nepheline in nephelinite from Hamada, Shimane Prefecture, Japan

AbstractK-rich nepheline with a structural formula of A2B6T14T24T34T44O32 (Z = 1) within melilite–olivine nephelinite from Hamada, Shimane Prefecture, Japan, was investigated to clarify its crystal structure and to determine cation distributions in the A and B structural positions of structural channels and tetrahedral T1–T4 sites. The chemical formula of a single-crystal sample was (Na5.437K2.248Mg0.034Ca0.031)Σ7.750(Si8.332Al7.445Fe3+0.158Ti0.009Cr0.005)Σ15.949O32, which results in 65.2, 27.8, 2.1, 3.2 and 1.6 mol.% NaAlSiO4, KAlSiO4, NaFe3+SiO4, □Si2O4 and □0.5(Ca,Mg)0.5AlSiO4 end-member components, respectively, where □ is a vacancy. X-ray diffraction data of a single crystal with dimensions of 0.28 mm × 0.15 mm × 0.05 mm measured at 296 K indicate the space group P63. In the structural refinement, the R1 factor was reduced to 3.69% by taking twinning by merohedry into the refinement. The refinement accounted for 77.7% of the absolute structure and 22.3% of the a and b axes reversed absolute structure. The atomic populations determined in the A and B positions were 1.834 K + 0.166 □ and 5.705 Na + 0.198 K + 0.031 Ca + 0.034 Mg, respectively, implying the substitution of K for Na in the B position. The a and c dimensions are a = 10.0270(3) and c = 8.4027(3) Å. The average &amp;lt;A–O&amp;gt; and &amp;lt;B–O&amp;gt; distances are 3.009 and 2.65 Å, respectively. The substitution of K for Na in the B channel results in increased volume and bond-length distortion of the BO8 polyhedra, which then reduces distortion of the AO9 polyhedra. The average T–O distances indicate that the T1 and T4 sites are essentially filled with Al, whereas the T2 and T3 are filled with Si. Despite the deviation of the O1 oxygen from the triad axis and the combination of K+ ions and vacancies in the hexagonal channels, an incommensurate structure was not observed in the X-ray diffraction data or using the electron diffraction technique.

Antenna Phase Center Calibration for Array InSAR System Based on Orthogonal Subspace

The array InSAR system obtains a three-dimensional image of an observed scene using a combination of pulse compression and synthetic and real aperture techniques. However, Antenna Phase Center (APC) errors can occur within a practical array InSAR system, which thus degrades the imaging quality in a height direction. The aim of this paper is to improve calibration problems occurring with APC errors. The effect of APC errors is analyzed, and a calibration method based on the orthogonal subspace principle is proposed that utilizes SAR Single Look Complex (SLC) to obtain the noise subspace through eigenvalue decomposition. The subspace orthogonal principle is then used to solve the APC positions of multiple channels simultaneously. In addition, a calibration scheme for the APC position is presented for application with an array InSAR system. The effectiveness of the proposed calibration method is verified using simulations and experimental results.