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Open Journal of Geology 2023年第1期13卷 1-22页

作者： Hilaire Elenga Nehl Dorland Kobawila Dieudonne Maurice Malounguila-Nganga malanda Nimy edmond Nicaise Giresse Pierre Geosciences Laboratory Faculty of Science and Technology Marien Ngouabi University Brazzaville Congo Geological and Mining Research Center (CRGM) Brazzaville Congo Center for Training and Research on Mediterranean Environments (CEFREM) University via Dominitia Perpignan France

A granulometric, mineralogical, morphoscopic and exoscopic study and Rock-Eval analysis carried out on samples taken in the Loango Bay and at Kivesso on the Congolese coast have made it possible to highlight the highly erosive character of the well-documented wet phases ca 9000 - 3000 years B.P. and ca 320 B.P. in the sub-region. Supported by carbon-14 dating, total organic carbon analyses highlight two major phases of peat deposit emplacement. The first, ca. 7000 years B.P., corresponds to the beginning of the deposition of the yellow formation in the entire Loango Bay;the second, ca. 320 years B.P., is contemporary with the deposition of peat in the Kivesso sector. The granulometric analysis of the sediments shows that they are essentially sandy-clay and very poor in silt, alternating with beds of silty clay sometimes rich in organic matter. These sands have a predominant mode of 0.200 mm and an average varying between 0.150 and 0.300 mm. They constitute the flood phase of the carrier current. They are associated with a population of mode 0.125 mm sometimes 0.050 mm with an average varying between 0.100 mm and 0.126 mm which corresponds to the settling phase. Morphoscopic examination showed several varieties of quartz that argue for a source of supply close to the depositional sites.

关键词： Holocene Paleoclimates Paleoenvironments Loango Bay Sedimentology

Sedimentology and Mineralogy of Surface Formations of the Mossendjo Area (Republic of Congo): Paleoenvironmental and Paleoclimatic Implications

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Open Journal of Geology 2021年第10期11卷 471-493页

作者： Jude Nogelvi Ngakosso Ngolo Hilaire Elenga Mambou Jean Romuald Malounguila Ganga Dieudonné malanda edmond Laboratory of Geosciences Faculty of Science and Technology Marien Ngouabi University Brazzaville Congo Geological and Mineral Research Center (CRGM) Brazzaville Congo

Studies undertaken at several sites in the Congolese basin and in the Chaillu massif are helping to reinterpret the sedimentological formations known as cover formations, which are widely exposed in Central Africa. This article presents the results of granulometric, morphoscopic, mineralogical and chemical analyzes obtained at three sites in the Chaillu. Gronulometric analysis indicates that the sands at the three sites are rated medium to high. The cumulative curves are essentially sigmoidal with regular and spreading slopes. This facies indicates that the deposition took place due to a banal and moderate variation in the competence of the carrier current. The morphoscopy of the quartz grains shows that they are mainly angular and shiny. These data reflect a relatively close source and transport by water. The synthesis of lithological, granulometric, petrographic and geochemical analyzes allowed us to highlight three episodes of deposits in the Mossendjo area: the first is characterized by a channel-type fluvial system marked by deposits from the hospital borehole and from the station;the second, which is alluvial, corresponds to the clogging of the channel. These two alluvial phases are overcome by a third, fluvial, channel-type episode, the end of which is marked by the establishment of the yellow formation. The vertical and lateral organization at the outcrop of this yellow formation has the same characteristics as those described earlier and in the sub-region where it was attributed to the wind-generated cover formation. This study thus highlights the existence of a wet phase during which two fluvial systems of non-contemporary channel types developed which overlap.

关键词： Sedimentology Fluvial System Paleoenvironment Mossendjo Congo

Bionic MEMS for Touching and Hearing Sensations: Recent Progress, Challenges, and Solutions

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Journal of Bionic Engineering 2022年第3期19卷 590-615页

作者： Chang Ge edmond Cretu Department of Electrical and Computer Engineering The University of British ColumbiaVancouverBCV6T 1Z4Canada

This paper reviews the recent progress on bionic microelectromechanical systems(MEMS)used for touching and hearing sensations,focusing on the following three types of devices:MEMS tactile sensors,MEMS directional microphones,and MEMS vector *** reviewing the electromechanical coupling principles,design,and performance of these MEMS devices,the authors conclude that it is vital for future research efforts in bionic MEMS to focus more on microfabrication *** development of robust microfabrication flows is the basis to implement hybrid electromechanical coupling principles based on novel functional ***-quality polymeric micromachining technologies can also significantly enhance the potential of existing bionic MEMS designs for more practical applications.

关键词： Bionic MEMS Tactile sensor Directional microphone Vector hydrophone Polymeric micromachining PDMS SU-8

A polymeric piezoelectric MEMS accelerometer with high sensitivity,low noise density,and an innovative manufacturing approach

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Microsystems & Nanoengineering 2023年第6期9卷 149-164页

作者： Chang Ge edmond Cretu The Department of Electrical and Computer Engineering The University of British ColumbiaVancouverCanada

The piezoelectric coupling principle is widely used(along with capacitive coupling and piezoresistive coupling)for MEMS *** MEMS accelerometers are used primarily for vibration *** piezoelectric MEMS accelerometers offer the merits of heavy-metal-free structure material and simple microfabrication *** importantly,polymeric piezoelectric MEMS accelerometers may be the basis of novel applications,such as fully organic inertial sensing microsystems using polymer sensors and organic integrated *** paper presents a novel polymer piezoelectric MEMS accelerometer design using PVDF films.A simple and rapid microfabrication flow based on laser micromachining of thin films and 3D stereolithography was developed to fabricate three samples of this *** proof-of-concept experiments,the design achieved a sensitivity of 21.82 pC/g(equivalent open-circuit voltage sensitivity:126.32 mV/g),a 5%flat band of 58.5 Hz,and a noise density of 6.02µg/√***,this design rivals state-of-the-art PZT-based counterparts in charge sensitivity and noise density,and it surpasses the performance capabilities of several commercial MEMS ***,this design has a 10-times smaller device area and a 4-times larger flat band than previous state-of-the-art organic piezoelectric MEMS *** experimentally validated performance metrics demonstrate the promising application potential of the polymeric piezoelectric MEMS accelerometer design presented in this article.

关键词： piezoelectric accelerometer noise

Polymeric piezoelectric accelerometers with high sensitivity,broad bandwidth,and low noise density for organic electronics and wearable microsystems

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Microsystems & Nanoengineering 2024年第3期10卷 63-74页

作者： Chang Ge edmond Cretu The Department of Electrical and Computer Engineering The University of British ColumbiaVancouverBCCanada

Piezoelectric accelerometers excel in vibration *** the emerging trend of fully organic electronic microsystems,polymeric piezoelectric accelerometers can be used as vital front-end components to capture dynamic signals,such as vocal vibrations in wearable speaking assistants for those with speaking ***,high-performance polymeric piezoelectric accelerometers suitable for such applications are *** organic compounds such as PVDF have inferior properties to their inorganic counterparts such as ***,most existing polymeric piezoelectric accelerometers have very unbalanced performance *** often sacrifice resonance frequency and bandwidth for a flat-band sensitivity comparable to those of PZT-based accelerometers,leading to increased noise density and limited application *** this study,a new polymeric piezoelectric accelerometer design to overcome the material limitations of PVDF is *** new design aims to simultaneously achieve high sensitivity,broad bandwidth,and low *** samples were manufactured and characterized,demonstrating an average sensitivity of 29.45 pC/g within a±10 g input range,a 5%flat band of 160 Hz,and an in-band noise density of 1.4μg/√*** results surpass those of many PZT-based piezoelectric accelerometers,showing the feasibility of achieving comprehensively high performance in polymeric piezoelectric accelerometers to increase their potential in novel applications such as organic microsystems.

关键词： piezoelectric polymeric overcome

Optimization designed large-stroke MEMS micromirror for adaptive optics

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Chinese Optics Letters 2010年第12期8卷 1163-1166页

作者：孙全 Kelly He edmond Cretu College of Optoelectronics Science and Engineering National University of Defense Technology Department of Electrical and Computer Engineering University of British Columbia

A novel micromirror based on the PolyMUMPs process is designed and presented. The hexagonal micromirror with a diameter of 450 μm consists of three supporting bilayer cantilevers and a mirror plate. The bilayer cantilevers, formed with a polysilicon layer and a gold layer, elevate the mirror plate according to residual stress-induced bending. Both analytical and finite element analysis （FEA） models are built to calculate the elevated height of the free end of the cantilever. The analytical solution is in accordance with the FEA simulation results, with longitudinal stresses applied only. Results of a three-dimensional （3D） simulation with two direction stresses applied also show the elevated height to be proportional to the width of the cantilever and the length of the gold layer. Due to the torque of the joint, the elevated heights of the two kinds of cantilevers assembled with the mirror plates are much smaller than those of the free end of the cantilevers. Both micromirrors with different cantilevers are fabricated. The elevated heights of the fabricated micromirrors are measured using Veeco optical profiler, which show good coincidence with simulation results.

关键词： Finite element method Microelectromechanical devices Mirrors Polysilicon Three dimensional Three dimensional computer graphics

Three trajectories for narrative visualisation

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Visual Informatics 2021年第2期5卷 26-40页

作者： Cameron edmond Tomasz Bednarz Expanded Perception&Interaction Centre(EPICentre) School of Art&DesignUNSWSydney NSWAustralia CSIRO’s Data61 Sydney NSWAustralia

Narrative Visualisation(NarVis)is the pairing of data visualisation with narrative *** to its interdisciplinary applications and scholarship,NarVis presentations often feature vastly different interpretations of"narrative"and"visualisation",which is echoed in NarVis authoring *** map the morphology of how the narratives of NarVis manifest,we identify three different trajectories for the *** trajectories are identified through an analysis of selected NarVis presentations and tools,with an emphasis on identifying how traditional narrative techniques are adopted,transposed or indeed challenged by NarVis *** then populate our categories with additional examples and tools,providing a foundational point of reference for NarVis scholars,authors and tool developers.

关键词： Visualisation Narrative techniques Communication Storytelling Interaction design

Equidistance target-following controller for underactuated autonomous underwater vehicles

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International Journal of Intelligent Computing and Cybernetics 2013年第2期6卷 108-125页

作者： Behzad Taheri edmond Richer Department of Mechanical Engineering Southern Methodist UniversityDallasTexasUSA

Purpose–Autonomous Underwater Vehicles(AUVs)play a crucial role in marine biology research and oceanic natural resources *** most AUVs are underactuated they require sophisticated trajectory planning and tracking *** purpose of this paper is to develop a new method that allows an underactuated AUV to track a moving object while constraining the approach to a direction tangent to the path of the ***,the distance at which the AUV follows the target is constrained,reducing the probability of detection and unwanted behavior change of the ***/methodology/approach–First,a kinematic controller that generates a trajectory tangent to the path of the moving target is designed such that the AUV maintains a prescribed distance and approaches the target from *** a Lyapunov based method the stability of the kinematic controller is ***,a dynamic sliding mode controller is employed to drive the vehicle on the trajectory computed in the first ***–The kinematic and dynamic controllers are shown to be stable and robust against parameter uncertainty in the dynamic model of the *** of numerical simulations for equidistant tracking of a target on both smooth and discontinuous derivatives trajectories for a variety of relative initial positions and orientations are ***/value–The contribution of this research is development of a new method for path planning and tracking of moving targets for underactuated AUVs in the horizontal *** method allows control of both the direction of approach and the distance from a moving object.

关键词： Trajectories Tracking Programming and algorithm theory Underwater technology Controllers Path planning and trajectory tracking Autonomous underwater vehicles Nonlinear robust control

Tracking facial features with occlusions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第7期7卷 1282-1288页

作者： MARKIN Evgeny PRAKASH edmond C. School of Computer Engineering Nanyang Technological University Singapore

Facial expression recognition consists of determining what kind of emotional content is presented in a human face. The problem presents a complex area for exploration, since it encompasses face acquisition, facial feature tracking, facial ex- pression classification. Facial feature tracking is of the most interest. Active Appearance Model (AAM) enables accurate tracking of facial features in real-time, but lacks occlusions and self-occlusions. In this paper we propose a solution to improve the accuracy of fitting technique. The idea is to include occluded images into AAM training data. We demonstrate the results by running ex- periments using gradient descent algorithm for fitting the AAM. Our experiments show that using fitting algorithm with occluded training data improves the fitting quality of the algorithm.

关键词： Active Appearance Model (AAM) Facial feature tracking Computer vision

Fabrication and testing of polymer-based capacitive micromachined ultrasound transducers for medical imaging

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Microsystems & Nanoengineering 2018年第1期4卷 178-189页

作者： Carlos D.Gerardo edmond Cretu Robert Rohling Department of Electrical and Computer Engineering University of British Columbia2332 Main MallVancouverBCCanada Department of Mechanical Engineering University of British Columbia6250 Applied Science LnVancouverBCCanada

The ultrasonic transducer industry is dominated by piezoelectric *** an emerging alternative,capacitive micromachined ultrasound transducers(CMUTs)offer wider bandwidth,better integration with electronics,and ease of fabricating large *** have a sealed cavity between a fixed electrode and a suspended metalized *** cost and sensitivity are limiting factors in current CMUTs that depend on the fabrication equipment and,especially,on the materials *** widespread use of CMUTs,a much lower fabrication cost that uses inexpensive materials,which maintain or improve upon existing sensitivity,is ***,a new fabrication process is described for polymer-based CMUTs(polyCMUTs)using the photopolymer SU-8 and *** first ultrasound B-mode image of a wire phantom created with a 64-element linear array using synthetic aperture beamforming techniques is presented.A 12 VAC signal superimposed on a 10 VDC signal was used on the transmission side,and only a bias-tee,with no amplifiers,was used on the receiving *** low operational voltage and high sensitivity of this device can be partially attributed to a pre-biasing condition on the *** using a novel sacrificial layer combined with a top electrode embedded inside the membrane,we demonstrated that SU-8 can be used to manufacture CMUTs ***,the fabrication used relatively simple equipment,and the number of fabrication steps was reduced compared to traditional CMUT *** new fabrication process has the potential to increase the use of CMUTs in the ultrasound market,including the market for wearable transducers.

关键词： polymer electrode testing