Outer Modulation Research Articles

Chirped flicker optoretinography for in vivo characterization of human photoreceptors' frequency response to light.

Flicker electroretinography (ERG) has served as a valuable noninvasive objective tool for investigating retinal physiological function through the measurement of electrical signals originating from retinal neurons in response to temporally modulated light stimulation. Deficits in the response at certain frequencies can be used as effective biomarkers of cone-pathway dysfunction. In this Letter, we present the progress we made on its optical counterpart-photopic flicker optoretinography (f-ORG). Specifically, we focus on the measurement of the response of light-adapted retinal photoreceptors to a flicker stimulus with chirped frequency modulation. In contrast to measurements performed at discrete frequencies, this technique enables a significantly accelerated characterization of photoreceptor outer segment optical path length modulation amplitudes in the nanometer range as a function of stimulus frequency, enabling the acquisition of the characteristic frequency response in less than 2 sec.

The mass production of silicon sensors for the Phase-2 CMS Outer Tracker

The high luminosity upgrade of the Large Hadron Collider (HL-LHC) will create a more challenging and demanding environment for the operation of the CMS detector. The peak instantaneous luminosity of the HL-LHC machine will reach 5–7 × 1034 cm-2s-1, which by the end of its lifetime will have delivered up to 4000 fb-1. To cope with these conditions the CMS Tracker will be fully replaced with a more advanced system. The new sub-detector is divided into an Outer Tracker, instrumented by short strips and macro pixels, and a more granular Inner Tracker using pixelated sensors. This report will describe some features of the new Outer Tracker silicon sensors and modules, provide results indicating the quality of the sensors produced to date, as well as the robustness of the sensors against environmental factors such as relative humidity.

Engineering Outer Membrane Vesicles to Increase Extracellular Electron Transfer of Shewanella oneidensis.

Outer membrane vesicles (OMVs) of Gram-negative bacteria play an essential role in cellular physiology. The underlying regulatory mechanism of OMV formation and its impact on extracellular electron transfer (EET) in the model exoelectrogenShewanella oneidensis MR-1 remain unclear and have not been reported. To explore the regulatory mechanism of OMV formation, we used the CRISPR-dCas9 gene repression technology to reduce the crosslink between the peptidoglycan (PG) layer and the outer membrane, thus promoting the OMV formation. We screened the target genes that were potentially beneficial to the outer membrane bulge, which were classified into two modules: PG integrity module (Module 1) and outer membrane component module (Module 2). We found that downregulation of the penicillin-binding protein-encoding gene pbpC for peptidoglycan integrity (Module 1) and the N-acetyl-d-mannosamine dehydrogenase-encoding gene wbpP involved in lipopolysaccharide synthesis (Module 2) exhibited the highest production of OMVs and enabled the highest output power density of 331.3 ± 1.2 and 363.8 ± 9.9 mW m-2, 6.33- and 6.96-fold higher than that of the wild-typeS. oneidensis MR-1 (52.3 ± 0.6 mW m-2), respectively. To elucidate the specific impacts of OMV formation on EET, OMVs were isolated and quantified for UV-visible spectroscopy and heme staining characterization. Our study showed that abundant outer membrane c-type cytochromes (c-Cyts) including MtrC and OmcA and periplasmic c-Cyts were exposed on the surface or inside of OMVs, which were the vital constituents responsible for EET. Meanwhile, we found that the overproduction of OMVs could facilitate biofilm formation and increase biofilm conductivity. To the best of our knowledge, this study is the first to explore the mechanism of OMV formation and its correlation with EET of S. oneidensis, which paves the way for further study of OMV-mediated EET.

Control of chatter vibration in double inserts turning with phase difference of modulations

A double inserts turning with two inserts mounted on a tool shank is proposed to control regenerative chatter vibration in turning of workpieces with low rigidity. In the presenting turning, the forward and the backward inserts are placed with a position offset in the feed direction; and those inserts are also clamped with a height offset each other in the cutter height direction. A part of the waved surface formed in the preceding cut by the forward insert is concurrently removed by the backward insert placed at a higher position than the rotation center of the workpiece. The regenerative effect, then, is controlled to suppress the chatter vibration by cutting the outer modulation with a time delay. This paper describes the principle of the double inserts turning for control of chatter vibration based on phase difference of the outer and the inner modulations. An analytical model, then, is presented to associate the regenerative effect with the offset parameters of the inserts. The cutting tests were conducted to verify the double inserts turning of a slender workpiece with the offset parameters of the inserts obtained by the analytical simulation. The chatter vibration is controlled effectively by adjusting the offset parameters of the inserts corresponding to the turning parameters.

Surface features of strongly heated bulk tungsten divertor plates at ASDEX Upgrade

• Horizontal cracks and humps at the surface were observed at ASDEX Upgrade solid tungsten divertor plates. • Recrystallization and grain growth is found at these locations. • High thermal stress due to temperature gradients is discussed to produce these cracks. • He bubble formation in tungsten is discusses as source of the surface humps. Solid tungsten tiles exposed at the outer strike point module of the ASDEX Upgrade divertor show cracks parallel to surface in the bulk and humps at the surface. At ASDEX Upgrade these horizontal cracks were observed for the first time. About 10 % of all tiles exhibit protrusions originated by horizontal cracks about 3-5 mm below the surface. The position of this damage coincidence with the location of highest deposited energy, which varies for the different tiles due to the mounting. The tungsten at the locations of the horizontal cracks exhibits recrystallization and grain growth, presumably due to the worse thermal contact caused by the horizontal cracks. Although, the operation of AUG was not hampered by these damages, these tiles had to be exchanged preventing progression of these damages. High thermal stress due to temperature gradients is discussed to originate these cracks. Additionally, humps are found at the surface at the position of high heat flux. Their occurrence seems to be related to the increased number of high power discharges. Focused ion beam prepared cross sections indicate pores and cavities in and below these humps. This finding is discussed in the view of He bubble formation in tungsten.

Numerical Analysis for Motion Response of Modular Floating Island in Waves

In recent years, modular-type floating islands have been considered as a promising option for future ocean space utilization. A modular floating island consists of a number of standardized pontoon-type modules and connectors between them. In this study, the motion responses of a modular floating island in waves was investigated based on frequency-domain numerical analysis. The numerical method is based on the potential flow theory and adopts a higher-order boundary element method with Green’s function. First, motion RAOs were directly compared with the model test data by reference to validate the present numerical method. Then, numerical investigations were conducted to analyze the motion characteristics of the floating island by considering various modules shapes and arrangements. It was found that motion responses were reduced in a single central module compared to when divided central modules were used. Finally, the effect of modular arrangement on the motion responses in irregular waves was discussed. It was confirmed that multiple-layer outer modules are more effective in calming the central module than using single-layer outer modules, except under very long period conditions.

Chatter suppression with productivity improvement by scheduling a [formula omitted] continuous feedrate to match spindle speed variation

Available spindle speed variation (SSV) methods, which are used to suppress regenerative chatter through disrupting the phase relationship between the inner and outer modulation on the machined surface, are usually performed in conjunction with the periodically varying feeds per tooth from the originally given constant feedrate. This article presents a new feedrate scheduling algorithm to match the SSV so that feed per tooth can be maximized during the whole machining. Concretely, a sinusoidal profile of feedrate is scheduled to match the designed SSV, meanwhile, the C3 continuous condition is guaranteed within all kinematic constraints. The feedrate is scheduled as two parts, i.e. a jerk continuous acceleration profile with the constant feedrate and a continuous sinusoidal profile above the constant feedrate. The continuity of the junction between these two parts is achieved through scheduling a gradually varying sinusoidal profile. To guarantee the kinematic constraints, the derivatives of the sinusoidal amplitude variation are obtained by the properties of trigonometric functions. As a result, a constant feed per tooth, which actually corresponds to the maximum of the periodically varying feeds per tooth associated with all existing SSV methods, is obtained, while the speed still periodically varies. It proves that the proposed scheduling algorithm can improve the machining efficiency since the feed per tooth is kept at the maximum level in most machining periods, and this is a great advancement over all existing SSV methods. Experiments confirm that chatter can be well suppressed with the significantly reduced machining time by using the proposed method.

A 56-Gb/s PAM-4 Transmitter/Receiver Chipset With Nonlinear FFE for VCSEL-Based Optical Links in 40-nm CMOS

This article presents a 56-Gb/s four-level pulse amplitude modulation (PAM-4) transmitter/receiver (TX/RX) chipset for optical link. The optical transmitter (TX) adopts a digital-to-analog converter (DAC)-based structure with a two-tap nonlinear PAM-4 feed-forward equalizer (FFE) implemented in the digital domain to compensate for the asymmetric responses from the vertical cavity surface-emitting laser (VCSEL). The 56-Gb/s PAM-4 receiver (RX) is connected to the photodiode (PD) and transimpedance amplifier (TIA) module for optical application. The interconnection loss from the RX chip to the PD+TIA module is compensated by the RX continuous-time linear equalizer (CTLE) and the one-tap decision-feedback equalizer (DFE). The pattern-filter-based bang-bang phase detector in the RX improves the jitter performance. Both TX and RX are fabricated in the 40-nm CMOS. The VCSEL TX demonstrates a 56-Gb/s compensated PAM-4 waveform with −0.9-dBm outer optical modulation amplitude (OMA) while consuming only 97 mW of power (1.73 pJ/b). The RX achieves 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−12</sup> bit error rate (BER) with 0.08 UI margin under 10-dB interconnection loss while dissipating 278 mW of power (4.96 pJ/b).

Thermal-Structural Analysis of the Support Structure for a Modular Space Deployable Antenna

A modular space deployable antenna has the advantages of extensibility, adaptability, and versatility, which is an ideal structure to meet the development trend of large aperture, high precision, and light weight for the deployable antenna in the future. To date, there are few reports on the temperature response of a modular deployable antenna in the thermal alternating environment in orbit. The aim of this study is at investigating the influence of a modular deployable antenna support structure on the surface accuracy and stability under the space thermal alternating environment. For this purpose, the thermal-structure analysis of the deployable antenna support structure was carried out by ANSYS APDL finite-element software. Using the transient temperature field obtained by thermal analysis as the boundary condition, the coupling law of stress development and thermal deformation of the support chord and cable caused by the antenna structure constraint position and other parameters is analyzed. In a uniform thermal field, the thermal stress of cables in the central module of the structure is the highest and that of the chord components in the same-circle modules is essentially the same. The thermally stress of the upper chords increases progressively toward the outer module, whereas that of cables decreases in the same direction. The thermal deformation at the upper-layer centroid of the structure can reach about 15 mm, so the influence on the accuracy of the antenna cannot be ignored. When the splicing vertical rod of adjacent modules in the outermost of the support structure is taken as the constraint connecting with the extension arm, the thermal deformation of the structure is minimum. The heat-insulating composite coating should be adopted on the surface of the antenna structure to reduce the thermal deformation and improve the adaptability. The thermal-structural analysis model proposed in this study could accurately estimate the behaviour of thermal deformation for the modular space deployable antenna, but the further coupling condition of the nonuniform temperature field could still be conducted. The results can provide a reference for the basic theory and engineering application of thermal-structural analysis for extralarge-aperture modular deployable antennas in the future.

Prototyping and qualification of 2S modules for the CMS Outer Tracker upgrade at the HL-LHC

In preparation for the High Luminosity LHC, the entire tracker detector of the CMS experiment will be exchanged as part of the Phase-2 Upgrade. The new Outer Tracker will comprise approximately 13,000 silicon sensor modules, of which 7608 are “2S modules” consisting of two parallel mounted silicon strip sensors, and 5592 are “PS modules” consisting of one pixel and one strip sensor in a single module. These modules provide tracking information to the level 1 trigger by correlating the hit information of both sensor layers, allowing discrimination of particle tracks by their transverse momentum. To guarantee successful operation during data-taking, the production of the outer tracker modules has to fulfill strict requirements. This note will discuss the assembly procedures as well as some key results of the electronic, thermal and vibration tests performed at CERN for qualifying the 2S module design and for preparing the module assembly procedures.

Session-Based Recommendation with GNN and Time-Aware Memory Network

The goal of the session-based recommendation system (SBRS) is to predict the user’s next behavior based on anonymous sessions. Since long-term historical information of users is not available, deep learning technology has become the mainstream technology in session-based recommendation systems instead of traditional content-based recommendation methods. However, most SBRS methods only consider the session itself, ignoring the collaborative information from other sessions. Even if some SBRS models consider collaborations between sessions, they mostly use the click order to calculate the similarity only and ignore the time the user spends on different items, which might imply the user’s varying interest on these items. In this paper, we propose a session-based recommendation model with GNN and time-aware memory networks (SR-GTM), which learns the user’s interest representation by combining the information from the session itself and the collaborative information from relevant neighbor sessions. Specifically, SR-GTM mainly includes inner feature extraction module (IFEM) and outer feature extraction module (OFEM). IFEM uses GNN to learn the session features based on its item sequence, and OFEM uses a memory network with dwell time information encoded to extract collaborative information. Finally, SR-GTM aggregates IFEM and OFEM by the gating mechanism and then decodes the output by a softmax layer to obtain the recommendation score for each candidate item. Experiments on three public datasets Yoochoose1/64, Yoochoose1/4, and RetailRocket show that SR-GTM achieves optimal performance compared with other state-of-the-art methods. More specifically, SR-GTM has improvements of 0.77%, 0.38%, and 3.63% over the best baseline method in P@20 and has improvements of 2.91%, 2.52%, and 2.49% in MRR@20, respectively.

Research on Scheduling Algorithm of Agricultural Machinery Cooperative Operation Based on Particle Swarm Neural Network

In order to improve the cooperative operation scheduling effect of agricultural machinery, this article uses particle swarm neural network to study the cooperative operation scheduling algorithm of agricultural machinery and improves the cooperative scheduling effect of intelligent agricultural machinery. Aiming at the mixed integer nonlinear programming problem, this article proposes a collaborative algorithm of population intelligence and linear programming. The outer layer of the algorithm uses the improved particle swarm algorithm IPSO module, the inner layer uses the simplex algorithm SIM module, and the optimal solution of the MINLP problem is obtained through the iterative update of the inner and outer modules. The experimental study shows that the cooperative operation scheduling model of agricultural machinery based on particle swarm neural network proposed in this article can play an important role in modern agricultural planting and effectively improve the efficiency of agricultural planting.

Integrating parametric design and additive manufacturing knowledge in industrial design education

Additive Manufacturing (AM) technologies are present in almost any industry. For industrial designers, AM technologies are important for prototyping of new design concepts, and for their evaluation in short time and with less effort. Physical prototypes in industrial design often represent the outer shape, main modules and basic motions proposed with the designed concept. They are useful for better communication and acceptance of the design. Efficient prototyping can support creativity and experimentation in design.However, AM technologies also have limitations, meaning that there are manufacturing restrictions that the designer needs to know. Lack of knowledge on DfAM tools and techniques can be seen as one of the barriers for the further implementation of AM. By implementing DfAM in the Industrial Design Engineering curriculum, future designers can work confidently with AM and design products that fully exploit the possibilities of these technologies. DfAM is a way of thinking, a way of designing that the future designers and engineers need to obtain in the educational process.In this paper, we present the learning process that connects parametric modelling, DfAM and AM technologies through practical examples of product modelling and prototyping. The product models are redesigned and physically prototyped by the students, using a selected AM technology. More advanced examples are introduced through student projects that can stimulate creativity in development of design ideas, based on improved understanding of how the objects are manufactured, to get more advantage from using AM technologies.

Two polygon-like beams generated by a modified interfering vortex spiral zone plate

A modified interfering vortex spiral zone plate (MIVSZP) is proposed to produce two polygon-like beams at the focal plane. A radial shift parameter t3 has influence on the shapes of two beams. When t3 has an appropriate value only, the MIVSZP has two polygon-like beams. With the increase of the inner phase modulation parameter t1, the rotation angle of the inner polygon-like beam increases firstly, then decreases and increases finally. When the outer phase modulation parameter t2 increases, the rotation angle of the inner polygon-like beam increases. However, t1 and t2 cannot make the outer polygon-like beam rotate. The topological charge p of the modified interfering vortex phase is equal to the number of sides of the polygon. In addition, for the arbitrary topological charge l of the spiral zone plate, the two polygon-like beams have the same topological charge equal to l. Moreover, it is proved in the simulations and experiments that the topological charges of two polygon-like beams can be identified by the number of fringes or spots generated by the interference binary phase transmittance. The method of constructing the MIVSZP is illustrated. The proposed zone plate is applicable to rotate particles located at different polygons simultaneously, and increase optical communication capacities.

Hydraulic assessment of cooling circuit for CFETR W/Cu divertor

Divertor, whose main functions are to sustain extremely high heat load and to exhaust impurity, is a key component in fusion reactor. CFETR divertor is currently under engineering design and technical validation phase. In this study, a cooling circuit design is proposed to obtain sufficient heat removal capability for CFETR divertor. The cooling circuit consists of two main modules which are outer target module and inner target module. Considering the complexity of the parallel cooling circuit concept, hydraulic characteristics is assessed and optimized for enough heat transfer capability and critical heat flux margin. Assessment of the hydraulic characteristics for the cooling circuit is performed by investigating flow velocity and local pressure on channels’ cross-sections. Uniform flow velocity of 10 m/s and acceptable critical heat flux margin higher than 1.4 in PFU coolants channels are obtained after optimization meeting the design requirements of the divertor.

Forward osmosis system design and optimization using a commercial cellulose triacetate hollow fibre membrane module for energy efficient desalination

This study is aimed at developing system mathematical design models to simulate and optimize a full scale forward osmosis (FO) for a hollow fibre membrane module for energy efficient desalination. Experimental data from a commercial outer selective CTA hollow fibre FO membrane module was used for validation. Less than 10% difference between the simulation and experimental results were observed which validated the reliability of the models. Simulation and design were performed for a 1000 m3/day FO plant using 0.6 M NaCl as draw solution (DS) (~seawater) and 0.02 M NaCl feed solution (FS) (~MBR effluent) to produce 0.25, 0.2 and 0.15 M NaCl diluted seawater to reduce the energy consumption of downstream pressure driven desalination process. A single element parallel module arrangement was found more suitable for this commercial hollow fibre membrane element. Finally, the numerical simulations revealed that to achieve 0.25, 0.20 and 0.15 M final DS concentrations, the optimum number of modules required were 370, 435 and 555 respectively considering membrane cost and energy consumption. The FO system using the commercial CTA hollow fibre module was found more energy efficient than a commercial TFC spiral wound membrane module.

Design of combined lower limb elastic compression device and comparative study with elastic bandage

To compared with the modified Robert Jones bandage of 3M elastic bandage, to evaluate the fitness, convenience, safety and comfort of the modular combination lower limb elastic compression device. Forty healthy adult college students, including 28 males and 12 females, aged 16 to 25 (20.3±2.2) years old and weighing 40 to 81 (60.4±20.2) kg, were randomly divided into two groups with 40 samples in each group. According to the body surface parameters of Chinese lower limbs and guided by the concept of modularization, a group of modular combined lower limb elastic compression device was designed. Each module was combined to evaluate the fitness of the modular combined compression device in thelength and circumference of the lower limbs. The left and right lower limbs were randomly paired and divided into groups, with 40 samples in each group. The convenience of the operation time, adjustment times and required time were compared between two groups. The safety of the two groups after 24 hours of application of pressure injury was compared. The subjective pain feeling changes within 24 hours were recorded by visual analogue scale (VAS) to evaluate the comfort. The device was composed of several elastic compression outer lining modules with different length and width of 15 cm, an inner lining module for buffering, positioning and attaching the main body, and an elastic ankle compression module. The length of the elastic compression outer lining module covers the circumference of the human lower limbs. The length of a single outer lining module increased from 15 cm to 80 cm every 5 cm interval, and the length of a single inner lining module increased from 62 cm to 83 cm every 3 cm interval. After the modules were selected and combined, the length and circumference of the lower limbs can reach 100% fitness. The operation time of the first placement(118.23±7.33) s and re operation(60.08±5.88) s of experimental group were significantly shorter than those of control group (164.68±8.93) s and re operation (131.23±7.91) s. The adjustment times (3) and operation time (3.50±0.71) s of experimental group were significantly shorter than those of control group(11)and operation time(139.00±5.66) s (P<0.05), but there was no significant difference between two groups (P>0.05). The VAS score of experimental group was significantly lower than that of control group at each time point (P<0.01). The modular combined elastic compression device has good fitness, better placement and flexible adjustment, convenience and safety, and better comfort than modified Robert Jones bandage of 3M elastic bandage.

Mobile app recommendation via heterogeneous graph neural network in edge computing

As a new computing technology proposed with the development of 5G, IoT technologies and increasing requirement of mobile applications and services, edge computing enables mobile application developers and content providers to serve context-aware mobile services (e.g., mobile app recommendation). Mobile app recommendation is known as an effective solution to overcome the information overload in mobile app markets. Most existing models only consider user-app interaction and feature modeling, and neglect the structural information which actually is a crucial part in the scenario of app recommendation. To fully exploit both structural and feature information for app recommendation, this paper proposes a novel heterogeneous graph neural network framework (HGNRec) including one inner module and one outer module. Specifically, the inner module is able to use a node-level attention to learn the importance between a node and its meta-path based neighbors. The outer module with a path-level attention can learn the importance of different meta-paths. With the learned importance from two modules, the comprehensive embeddings for user and app nodes can be generated by integrating features from meta-path based neighbors. Extensive experiments on the real-world Google Play mobile app dataset demonstrate the effectiveness of HGNRec.

Attention in Attention Networks for Person Retrieval.

This paper generalizes the Attention in Attention (AiA) mechanism, in P. Fang et al., 2019 by employing explicit mapping in reproducing kernel Hilbert spaces to generate attention values of the input feature map. The AiA mechanism models the capacity of building inter-dependencies among the local and global features by the interaction of inner and outer attention modules. Besides a vanilla AiA module, termed linear attention with AiA, two non-linear counterparts, namely, second-order polynomial attention and Gaussian attention, are also proposed to utilize the non-linear properties of the input features explicitly, via the second-order polynomial kernel and Gaussian kernel approximation. The deep convolutional neural network, equipped with the proposed AiA blocks, is referred to as Attention in Attention Network (AiA-Net). The AiA-Net learns to extract a discriminative pedestrian representation, which combines complementary person appearance and corresponding part features. Extensive ablation studies verify the effectiveness of the AiA mechanism and the use of non-linear features hidden in the feature map for attention design. Furthermore, our approach outperforms current state-of-the-art by a considerable margin across a number of benchmarks. In addition, state-of-the-art performance is also achieved in the video person retrieval task with the assistance of the proposed AiA blocks.

Quantifying the performance advantage of using passive solar air heater with chimney for photovoltaic module cooling

The foreseeable growth of photovoltaic (PV) systems highlights the prominence of improving its efficiency. The performance of PV module deteriorates as a major part of irradiance is converted to heat. Amongst several PV thermal management techniques, passive air cooling is gaining importance due to its self-sustained nature. In the present experimental study, the performance of conventional solar air heater is enhanced by incorporating chimney. Further, by placing the PV module in the airflow path, its performance is improved compared to an identical module kept open to ambient. During testing, a maximum system efficiency of 35% was observed as air heater contributes to the maximum thermal efficiency of 25%. Further, due to better airflow over the PV module rear surface, a 13% reduction in surface temperature was observed compared to the outer module, which gave a 6% rise in power output. In such a combi system, the working of both PV and air heater complements the advantage to each other. Hence, the total efficiency of the air heater and PV module as two separate entities is always less than the system efficiency of the combi system.