Small Footprint Size Research Articles

A small sauropod trackway from the Upper Cretaceous Jindong Formation (Cenomanian), Goseong County, South Korea

In 2000, a small sauropod trackway was discovered in the Upper Cretaceous Jindong Formation (Cenomanian) at Eosin-ri, Goseong County, South Korea. This quadrupedal trackway consists of 34 very small sauropod footprints, with an average manus width of 10.0 cm and pes length of 12.8 cm, showing low heteropody (mean IPS/IMS: 1.38). The manus tracks are oval to kidney-shaped, while the pes tracks are generally subcircular to V-shaped, lacking distinct claw marks. The trackway shows a medium to wide gauge (mean PTR: 38.8%; WAP/PL: 1.18). The small footprint size and estimated trackmaker body size suggest that the trackmaker was an early juvenile titanosauriform sauropod based on the contemporaneous sauropod taxa of East Asia. Sauropod trackways reported from the Jindong Formation, including the Eosin-ri trackway, exhibit a tendency for narrower trackway gauges as pes length increases. This negative correlation between trackmaker size and trackway gauge may imply ontogenetic or behavioral variations within the same clade of sauropods or differences in gait or body plan amongst different sauropod taxa.

JPSS-1 ATMS Postlaunch Active Geolocation Analysis

A NOAA-20 (N20) Advanced Technology Microwave Sounder (ATMS) active geolocation (GEO) test was performed around January 2018 with 24 preselected coastline crossing scenes. After a comprehensive analysis of ATMS stare data and the corresponding Visible Infrared Imaging Radiometer Suite (VIIRS) data, the ATMS pitch, roll, and yaw pointing angle errors are found from the nadir perpendicular, the nadir oblique shallow angle, and the off-nadir perpendicular coastline crossing data, respectively. In this study, we first determine the ATMS radiometric coastline crossing time by using the ATMS radiometric count data. Since the coastline can be located anywhere within one ATMS field of view (FOV) from the passive (regular scanning) GEO data, depending on the scan starting time, it is not a valid assumption for the inflection point being the same as the coastline location. Consequently, using the passive GEO data to validate the sensor’s on-orbit pointing angle performance is limited. After finding the ATMS radiometric coastline crossing time from the ATMS data, we compare it with the VIIRS effective time stamp. Specifically, the VIIRS M3, M4, and M5 (true color) and M15 and M16 bands (thermal) data have a much smaller footprint size. Using the differences of the ATMS and VIIRS (effective) coastlines crossing times, the N20 ATMS pitch, roll, and yaw pointing angle errors are found to be −0.09°, −0.24°, and 0.28°, respectively. To determine ATMS GEO properly, these on-orbit pointing errors need to be corrected, adding to the ATMS sensor data record (SDR) processing coefficient table, and passed on to the operational GEO processing code.

PRELIMINARY QUALITY ANALYSIS OF GF-7 SATELLITE LASER ALTIMETER FULL WAVEFORM DATA

Abstract. The full-waveform data is the core data of GaoFen-7 (GF-7) satellite laser altimeter, and evaluation of waveform data quality is an important step and premise for satellite laser altimetry and quality control. In this paper, the full waveform data quality assessment and analysis of GF-7 laser altimeter is implemented during the period of on-orbit experiment, and the real waveform data of many orbits is used to quantitatively describe the characteristic parameters of the transmitted waveform and the signal-to-noise ratio (SNR), and the result of two beam lasers is compared. The conclusion is validated that the GF-7 laser altimeter can obtain effective waveform data and the echo waveform availability of the experimental data is approximate 72.59%, moreover, the quality of beam 1 is slightly better than that of the beam 2. The laser temperature is an important indication of the quality of transmitted waveform according to the SNR changing. The good SNR value of the waveform and small footprint size will be helpful for the terrain information extraction and analysis, although the repetition frequency is low.

Three Dimensional Radiative Effects in Passive Millimeter/Sub-Millimeter All-sky Observations

This study was conducted to quantify the errors prompted by neglecting three-dimensional (3D) effects, i.e., beam-filling and horizontal photon transport effects, at millimeter/sub-millimeter wavelengths. This paper gives an overview of the 3D effects that impact ice cloud retrievals of both current and proposed (Ice Cloud Imager) satellite instruments operating at frequencies of ≈186.3 and ≈668 GHz. The 3D synthetic scenes were generated from two-dimensional (2D) CloudSat (Cloud Satellite) observations over the tropics and mid-latitudes using a stochastic approach. By means of the Atmospheric Radiative Transfer Simulator (ARTS), three radiative transfer simulations were carried out: one 3D, one independent beam approximation (IBA), and one-dimensional (1D). The comparison between the 3D and IBA simulations revealed a small horizontal photon transport effect, with IBA simulations introducing mostly random errors and a slight overestimation (below 1 K). However, performing 1D radiative transfer simulations results in a significant beam-filling effect that increases primarily with frequency, and secondly, with footprint size. For a sensor footprint size of 15 km, the errors induced by neglecting domain heterogeneities yield root mean square errors of up to ≈4 K and ≈13 K at 186.3 GHz and 668 GHz, respectively. However, an instrument operating at the same frequencies, but with a much smaller footprint size, i.e., 6 km, is subject to smaller uncertainties, with a root mean square error of ≈2 K at 186.3 GHz and ≈7.1 K at 668 GHz. When designing future satellite instruments, this effect of footprint size on modeling uncertainties should be considered in the overall error budget. The smallest possible footprint size should be a priority for future sub-millimeter observations in light of these results.

Bloch-surface-wave photonic crystal nanobeam cavity

We theoretically demonstrate a nanobeam cavity based on a photonic crystal ridge that supports localized Bloch surface waves (BSWs) propagating at the truncation interface of a periodic multilayer. Combining the appealing characteristics of a nanobeam cavity (such as flexible geometry, small footprint size, and an etching-free fabrication with the leading lithographic technologies) with the versatility of BSW (whose dispersion relation is finely tunable as compared to other surface waves), this structure may prove to be a customizable visible-to-IR platform, well suited for a number of applications ranging from optical sensing to the control of single-photon emission from embedded nanoemitters such as quantum dots or color centers.

Miniaturised quadrature hybrid coupler using composite planar transmission lines

In this Letter, a novel miniaturisation technique for a 3-dB quadrature hybrid coupler is described. The revolutionary structure is composed of folded microstrip lines and folded coplanar waveguides that are printed on the top- and bottom-surfaces of a dielectric substrate, respectively. The two different planar lines are connected by copper vias to form the double-path composite microstrip-coplanar waveguide (CMCPW) line. To demonstrate the effectiveness of the technique, a simple yet miniaturised hybrid coupler is devised by introducing folded S-shaped CMCPW-lines, wherein their lengths are gradually changed to address the design goals. The simulated and measured results of the proposed coupler validate its good performance metrics in the amplitude responses of power splitting, return- and insertion-loss. Moreover, its isolation and quadrature phase between outputs have been examined. A very small footprint size of 0.0667 λ 0 × 0.0667 λ 0 at 0.5 GHz has been realised.

An automated (novel) algorithm for estimating green vegetation cover fraction from digital image: UIP-MGMEP.

Green vegetation cover fraction (VCF) is an important indicator of vegetation status in ecology and agronomy. Digital image analysis (DIA) has been widely accepted as a new VCF measurement technique. In this study, we present a novel fully automatic threshold segmentation algorithm for VCF measurements, which is named as upper inflection point plus mean gradient magnitude of edge pixels (UIP-MGMEP). The algorithm performs VCF estimation upon the vegetation index Excess Green (EXG). UIP-MGMEP optimizes the EXG threshold by searching the upper inflection point (UIP) of the M-Et curve (mean gradient magnitude of edge pixels (MGMEP) vs. EXG threshold), based on the assumption that EXG variance of the boundary pixels between vegetation and background is larger than the variance of the background. Five typical sample images are used to illustrate how ground complexity reduces the distinctness of the UIP. Three controlled experiments are illustrated to test the robustness of UIP-MGMEP to resolution, exposure, and ground complexity. The results show that UIP-MGMEP is a promising algorithm for automatic VCF estimation upon digital images. Compared to broad-leaved grass, narrow-leaved grass is more sensitive to resolution and exposure. To reduce ground complexity, smaller footprint size while more images to cover the same area may be better than one image with large footprint size. UIP-MGMEP is fully automatic, making it promising for batch processing of VCF measurements that is very difficult in any wide-range field survey in the past. UIP-MGMEP algorithm can only extract green vegetation and is not suitable for non-green (even grayish-green) vegetation, due to the limits of vegetation index EXG. In addition, UIP-MGMEP is not recommended for images with VCF less than 0.5% or greater than 99.5%.

Generating 2-dimensional concentration gradients of biomolecules using a simple microfluidic design.

This study reports a microfluidic device for generating 2-dimensional concentration gradients of biomolecules along the width and length of a chamber and conventional 1-dimensional gradients along the width of its lateral parallel channels. The gradient profile can be precisely controlled by the applied flow rate. The proposed design is simple and straightforward, has a small footprint size compared to previously reported devices such as tree-shape designs, and for the first time, provides capability of generating desired 2D and 1D gradients, simultaneously. The finite element simulation analysis proves the feasibility of the microfluidic device, and the fluorescently labelled IgG antibody is used to demonstrate generated chemical gradients. This simple microfluidic device can be implemented for a wide range of high-throughput concentration gradient applications such as chemotaxis, drug screening, and organs-on-chips.

Design and Modeling of Polysilicon Electrothermal Actuators for a MEMS Mirror with Low Power Consumption.

Endoscopic optical-coherence tomography (OCT) systems require low cost mirrors with small footprint size, out-of-plane deflections and low bias voltage. These requirements can be achieved with electrothermal actuators based on microelectromechanical systems (MEMS). We present the design and modeling of polysilicon electrothermal actuators for a MEMS mirror (100 μm × 100 μm × 2.25 μm). These actuators are composed by two beam types (2.25 μm thickness) with different cross-section area, which are separated by 2 μm gap. The mirror and actuators are designed through the Sandia Ultra-planar Multi-level MEMS Technology V (SUMMiT V®) process, obtaining a small footprint size (1028 μm × 1028 µm) for actuators of 550 µm length. The actuators have out-of-plane displacements caused by low dc voltages and without use material layers with distinct thermal expansion coefficients. The temperature behavior along the actuators is calculated through analytical models that include terms of heat energy generation, heat conduction and heat energy loss. The force method is used to predict the maximum out-of-plane displacements in the actuator tip as function of supplied voltage. Both analytical models, under steady-state conditions, employ the polysilicon resistivity as function of the temperature. The electrothermal-and structural behavior of the actuators is studied considering different beams dimensions (length and width) and dc bias voltages from 0.5 to 2.5 V. For 2.5 V, the actuator of 550 µm length reaches a maximum temperature, displacement and electrical power of 115 °C, 10.3 µm and 6.3 mW, respectively. The designed actuation mechanism can be useful for MEMS mirrors of different sizes with potential application in endoscopic OCT systems that require low power consumption.

Investigation of a low-voltage polymeric 2 × 2 Mach-Zehnder interferometer optical switch using five-serial-coupled electro-optic microrings

Structure and design scheme of a Mach-Zehnder interferometer (MZI) EO switch, whose one arm is assisted by five serial-coupled microrings, is proposed and optimized. Using the derived formulas and expressions of output power, insertion loss and crosstalk, detailed design and optimization are performed. Under 1550-nm wavelength, analysis results indicate that the device can perform normal switching function and the low switching voltage is as low as 0.99V. The insertion loss is 1.15dB at bar state, whereas that is 1.97dB at cross state; the crosstalk is −17.8dB at bar state, whereas that is −12.3dB at cross state. The voltage-length product of the proposed switching device is about 0.21V·mm, which is 32 times smaller than that of the traditional MZI EO switch (6.69V·mm) with the same waveguide and electrode parameters. Therefore, due to small footprint size and extremely low switching voltage, this switching configuration can be densely integrated onto optoelectronic chips.

EmSBot

Component-based approaches are prevalent in software development for robotic applications due to their reusability and productivity. In this article, we present an Embedded modular Software framework for a networked ro BoTic system (EmSBoT) targeting resource-constrained devices such as microcontroller-based robots. EmSBoT is primarily built upon μCOS-III with real-time support. However, its operating system abstraction layer makes it available for various operating systems. It employs a unified port-based communication mechanism to achieve message passing while hiding the heterogeneous distributed environment from applications, which also endows the framework with fault-tolerant capabilities. We describe the design and core features of the EmSBoT framework in this article. The implementation and experimental evaluation show its availability with small footprint size, effectiveness, and OS independence.

Design of a microelectromechanical systems microgripper with integrated electrothermal actuator and force sensor

This article presents the conceptual design of a novel compliant microelectromechanical systems (MEMS)-based gripper with integrated electrothermal actuator and electrothermal force sensor. By this design solution, the device possesses some unique characteristics including a small and compact footprint size, and a large driving force by the thermal actuator. Owing to the use of a compliant rotational bearing, a large gripping range is obtained. The sensing arm has a capability of detecting the force transmitted from the left arm so as to prevent the damage of the grasped object. Analytical models are developed to evaluate the statics and dynamics performance of the gripper. Simulation results show that the thermal actuator produces sufficient gripping force to execute the gripping operation with a range of 80 µm under a low input voltage of 6 V. Moreover, the results of the established theoretical models match well with the finite element analysis (FEA) simulation results, which verifies the feasibility of the proposed gripper design.

Gain-switched Ti:sapphire laser-based photoacoustic imaging.

We demonstrate photoacoustic (PA) imaging using a compact gain-switched Ti:sapphire laser. Additionally, a simple laser configuration is provided. The Ti:sapphire laser is pumped using a frequency-doubled pulsed neodymium-doped yttrium aluminum garnet pulse laser operating at a repetition rate of 10Hz, with a pump energy of 37mJ. No water cooling is required for the Ti:sapphire crystal. The output pulse energy and pulse duration of the laser are 13.6mJ and 11ns, respectively. Thus, the power conversion efficiency is 36.7%. As the end mirror in a laser cavity is adjusted in a horizontal direction, the output wavelength can be tuned within a range of 725-880nm with a spectral bandwidth of approximately 1nm. The laser has a small footprint size of 50 cm×35 cm including even laser pumping. Because the near-infrared region has significant advantages in the context of absorption and scattering in biological tissues, our laser can be used for PA imaging. Apart from obtaining PA images of a tube filled with indocyanine green immersed in water and placed under chicken breast tissue, our laser system could also be used for the simultaneous PA and ultrasound (US) dual-modality imaging of blood vessels lying beneath the skin of a human middle finger. We used a commercially available US machine for the PA and US dual-modality imaging.

A small-footprint context-independent HMM-based synthesizer for Tamil

A text-to-speech synthesis system produces intelligible and natural speech corresponding to any given text. Two main attributes of a synthesizer are the quality of speech produced and the footprint size. In the current work, HMM-based speech synthesizers have been built and assessed using various kinds of phone-sized units, namely, monophone, triphone, triphone with contextual features, pentaphone, and pentaphone with contextual features. It is observed that the quality of synthetic speech improves with the addition of contexts, with a mean opinion score (MOS) of 2.4 for a synthesizer that uses monophones and 3.98 for one that uses pentaphones with 48 additional contextual features (pentaphone+). However, the footprint size also increases from 269 to 1840 kB, with the addition of contextual information. Therefore, based on a desired application, a compromise has to be made either on the quality or the footprint size. Analysis reveals that although speech synthesized by a monophone-based system lacks naturalness, it is intelligible. The lack of naturalness is primarily due to the discontinuities in the pitch contour. Therefore, an attempt is made to improve the quality of synthesized speech by smoothening the pitch contour, thereby retaining the small footprint size, while attaining quality of a synthesizer that uses contextual information. It is observed that smoothening the pitch contour at the word-level yields the best quality, with an MOS of 3.4. Further, a preference test reveals that 71.25 % of the sentences are similar in quality to the speech synthesized by a pentaphone+ HTS, while 5 % are better.

Linearized electro-optic racetrack modulator based on double injection method in silicon.

Racetrack-based modulator of increased linearity for optical links is presented and analyzed. The modulator is referred to as FLAME - Finer Linearity Amplitude Modulation Element. Linearity is improved via the introduction of a Double Injection approach. Large spurious-free-dynamic-range (SFDR) of 132dB·Hz(4/5) can thus be theoretically obtained. The FLAME is studied for silicon platform and requires small footprint size (100 × 50µm2) and low operation voltage, 2.5V. This makes the FLAME an appealing candidate for large scale integration in RF photonics.

DESIGN OF A LOW LOSS SILICON BASED HYBRID DIELECTRIC-LOADED PLASMONIC WAVEGUIDE AND A COMPACT HIGH PERFORMANCE OPTICAL RESONATOR

Here we present the design of a low loss top metal silicon (Si) hybrid dielectric-loaded plasmonic waveguide (TM-SiHDLW) and a compact, high performance optical resonator by numerical simulation based on finite element method. The waveguide adopted a thick (200 nm) top metal stripe structure to yield optimal performance due to reduced Ohmic loss in conductor around the stripe edge/corner. Moreover, a relatively thick (150 nm) dielectric spacer between the Si ridge and the metal stripe was employed to achieve both long propagation length and good field confinement. The effect of a thin (10 nm) silicon nitride (SiNx) layer covering the waveguide which was added for minimizing uncertainties on optical properties of SiHDLW resulting from high density of dangling bonds on Si surface was also investigated. Simulation results show that there is no significant degradation on the performance of the TM-SiHDLW. For the proposed plasmonic waveguide, a propagation length of 0.35 mm and a mode area around 0.029µm 2 were demonstrated. The TM-SiHDLW waveguide was then used as the basis for an optical resonator, which was designed to operate at the fundamental TE011 mode for yielding high quality factor at a relatively small footprint size. A metal enclosure was also adopted to reduce the radiation loss, and a high quality factor of ∼1900 was obtained, more than double the results in other disk or ring resonators of comparable size. Compared to the resonators based on a rounded top metal Si hybrid dielectric-loaded plasmonic waveguide (RTM-SiHDLW) which has a much longer propagation length than the TM-SiHDLW, as reported in our previous work, the performance is essentially the same. This is simply because, for the resonators, the radiation loss is the dominate loss mechanism and the dissipation in the waveguide structure itself, thus, contribute little to the final quality factor of the plasmonic resonators.

Application of Physically-Based Slope Correction for Maximum Forest Canopy Height Estimation Using Waveform Lidar across Different Footprint Sizes and Locations: Tests on LVIS and GLAS

Forest canopy height is an important biophysical variable for quantifying carbon storage in terrestrial ecosystems. Active light detection and ranging (lidar) sensors with discrete-return or waveform lidar have produced reliable measures of forest canopy height. However, rigorous procedures are required for an accurate estimation, especially when using waveform lidar, since backscattered signals are likely distorted by topographic conditions within the footprint. Based on extracted waveform parameters, we explore how well a physical slope correction approach performs across different footprint sizes and study sites. The data are derived from airborne (Laser Vegetation Imaging Sensor; LVIS) and spaceborne (Geoscience Laser Altimeter System; GLAS) lidar campaigns. Comparisons against field measurements show that LVIS data can satisfactorily provide a proxy for maximum forest canopy heights (n = 705, RMSE = 4.99 m, and R2 = 0.78), and the simple slope correction grants slight accuracy advancement in the LVIS canopy height retrieval (RMSE of 0.39 m improved). In the same vein of the LVIS with relatively smaller footprint size (~20 m), substantial progress resulted from the physically-based correction for the GLAS (footprint size = ~50 m). When compared against reference LVIS data, RMSE and R2 for the GLAS metrics (n = 527) are improved from 12.74–7.83 m and from 0.54–0.63, respectively. RMSE of 5.32 m and R2 of 0.80 are finally achieved without 38 outliers (n = 489). From this study, we found that both LVIS and GLAS lidar campaigns could be benefited from the physical correction approach, and the magnitude of accuracy improvement was determined by footprint size and terrain slope.

Low-voltage and compact polymeric optical switches using a Mach–Zehnder interferometer and N side-coupled electro-optic microrings

Universal structure and thorough analysis were proposed for a kind of polymer optical switch using N-th order microring resonator side-coupled Mach–Zehnder interferometer (MRR-SC-MZI). Formulation and expression of output power, insertion loss and crosstalk were derived, and detailed design and optimization were carried out. Analytical results indicate that all devices for N≥1 can perform normal switching function, and 8≥N≥2 is preferred for dropping the driving voltage below 5V. For the seven MRR-SC-MZI EO switches (N=2–8) whose cross-state voltages are within 0–2.32V, their bar-state voltages are within 0.96–4.83V and their insertion losses are within 0.35–0.85dB at bar state, whereas those within 0.14–1.70dB at cross state; their crosstalk are within −20.79 to −31.11dB at bar state, whereas those are within −13.86 to −20.36dB at cross state; their 3-dB electrical bandwidths are within 18.5–28.0GHz, and 3-dB optical bandwidths for the two output ports are within 18.1–40.0GHz and 32.0~55GHz, respectively. Comparison indicates that the driving voltages of the proposed MRR-SC-MZI switching devices are 10–250 times smaller than those of the traditional MZI EO switches with the same EO region length, device length and structural parameters. Therefore, due to small footprint size and low driving voltage, this switching configuration can be densely integrated onto optoelectronic chips.

Environment mismatch compensation using average eigenspace-based methods for robust speech recognition

The performance of speech recognition systems is adversely affected by mismatch between training and test conditions due to environmental factors. In addition to the case of test data from noisy environments, there are scenarios where the training data itself is noisy. In this study, we propose a series of methods for mismatch compensation between training and test environments, based on our "average eigenspace" approach. These methods are also shown to be effective for non-stationary mismatch conditions. An advantage is that there is no need for explicit adaptation data since the method is applied to incoming test data to find the compensatory transform. We evaluate these approaches on two separate corpora which are collected from realistic car environments: CU-Move and UTDrive. Compared with a baseline system incorporating spectral subtraction, highpass filtering and cepstral mean normalization, we obtain a relative word error rate reduction of 17---26 % by applying the proposed techniques. These methods also result in a dimensionality reduction of the feature vectors allowing for a more compact set of acoustic models in the phoneme space, a property important for automatic speech recognition for small footprint size mobile devices such as cell-phone or PDA's which require ASR in diverse environments.

Theoretical investigation of a polymer Mach–Zehnder electro-optic switch using 2N + 1 serial-coupled microrings with ultralow-driving voltage

Universal structure and thorough analysis are proposed for a kind of (2N + 1)th order polymer microring resonator Mach–Zehnder interferometer (MRR-MZI) electro-optic (EO) switch. Formulas and expressions of output power, insertion loss and crosstalk are derived, and detailed design and optimization are carried out. Analytical results indicate that, besides the first-order MRR-MZI EO switch (N = 0), other devices for N ≥ 1 can all perform normal switching function, and 5 ≥ N ≥ 2 is preferred for dropping the crosstalk below −10 dB. For the four MRR EO switches (N = 2–5), their switching voltages are 0.99, 0.73, 0.57 and 0.47 V, respectively; their insertion losses are within the range of 1.15–2.26 dB at bar state, whereas those are within the range of 1.95–2.42 dB at cross state; their crosstalks are within the range of 11.04–17.82 dB at bar state, whereas those are within the range of 10.34–12.51 dB at cross state. Compared with the traditional MZI EO switch, the voltage–length product (0.21 V mm) of this switching element is decreased by ~111.7 times under the same waveguide parameters. Therefore, due to small footprint size and extremely low switching voltage, this switching configuration can be densely integrated onto optoelectronic chips.