Orientation Control Research Articles

Fabrication of highly b-oriented MFI zeolite film over broad temperature window

Despite that oriented MFI zeolite films exhibit significant prospects for a wide range of applications due to microstructural superiority, their precise orientation control entails rigorous demands on reaction conditions (e.g., reaction temperature). In this work, we achieved facile synthesis of continuous b-oriented MFI zeolite films with few twins over a wide crystallization temperature range of 30–210 °C through adopting NH4F-mediated gel as nutrient during epitaxial growth. Both ammonium ions and fluorine ions were found crucial for enhancing the gel reactivity, endowing epitaxial growth with higher crystallization rates; moreover, the above morphology could be maintained even under fluctuating temperature conditions during film processing, thereby showing great potential for their bath production in a facile and reproducible manner.

Variable orientation in material extrusion of short carbon fiber reinforced polymer composites with high thermal conductivity

Controllable orientation architecture possesses tunable thermal behavior for effective heat dissipation in unidirectional product fields, meanwhile without interference with adjacent components. Herein, we proposed a variable orientation strategy in material extrusion of short carbon fiber (SCF) reinforced polymer composites framework with spatially tunable thermal properties. It was achieved due to the following reasons: (Ⅰ) Inherent shear flow in the nozzle; (Ⅱ) Increasing tensile flow by changing the ratio between the printing speed of monofilament and the feeding speed of filament (Vp/f); (Ⅲ) Further surface tension due to thinning monofilament by varying Vp/f. The SCF with different orientations and content reinforced polyether-ether-ketone (PEEK) composites were successfully fabricated. The microcosmic orientation of SCF could be programmed from a three-layer hierarchical framework to a single-layer oriented framework at different Vp/f. Benefit from variable orientation, the through-plane thermal conductivity of SCF/PEEK composites achieved a thermal conductivity enhancement of 173.9 %. In addition, the simulated application of SCF/PEEK composites in the CPU of the computer showed excellent heat transfer during heating. Further, the thermal conductivity mechanism of the synergistic influence between Vp/f and SCF content was analyzed by cross-sectional microstructure. The proposed strategy in this work for fabricating variable orientation of SCF reinforced polymer composites showcases great application prospects in electronic devices and unidirectional product fields.

Indirect Field Oriented Control of Induction Motor

The various control strategies for the control of the inverter-fed induction motor have provided good steady-state but poor dynamic response. In the last decades, many control techniques have been developed providing good performance. Field-oriented control is one of the most significant control methods for high performance AC electric machines and drives. In particular, for induction machines, indirect field oriented control is a simple and highly reliable scheme which has essentially become an industry standard. With the advent of the vector control methods, an induction motor can be operated like a separately excited dc motor for high performance applications. The speed control is observed in closed-loop control applications. The speed regulation is achieved with a PI controller which converts the command speed into the command torque and therefore the speed of the drive. In this paper PI controller base indirect field orientation control of 3-phase 415V, 50Hz Induction motor using cascaded multilevel inverter is proposed in MATLAB/SIMMLINK 7.10.0 (R2010a).

Effect of Energy-driven Molecular Precursor Decomposition on the Crystal Orientation of Antimony Selenide Film and Solar Cell Efficiency.

Antimony selenide (Sb2Se3) consists of 1D (Sb4Se6)n ribbons, along which the carriers exhibit high transport efficiency. By adjusting the deposition parameters of vacuum-deposited methods, such as evaporation temperature, chamber pressure, and vapor concentration, it is possible to grow the (Sb4Se6)n ribbons vertically or highly inclined towards the substrate, resulting in films with [hk1] orientation. However, the specific mechanisms by which these deposition parameters affect the orientation of thin films require a deeper understanding. Herein, a molecular beam epitaxy technique is developed for the preparation of highly [hk1]-oriented Sb2Se3 films, and the effect of evaporation parameters on the film orientation is investigated. It is found that the evaporation temperature can affect the decomposition degree of Sb2Se3, which in turn determines the vapor composition and film orientation. Additionally, the decomposition of Sb2Se3 related to evaporation temperature leads to significant changes in the elemental composition of the film, thereby passivating deep-level defects under Se-rich conditions. Consequently, the Sb2Se3 films with highly [hk1] orientation achieve a power conversion efficiency of 8.42% for the solar cells. This study provides new insights into the control of orientation in antimony-based chalcogenide films and points out new directions for improving the photovoltaic performance of solar cells.

Miniaturized Variable Stiffness Gripper Locally Actuated by Magnetic Fields

In minimally invasive surgery, grippers are essential for tissue manipulation. However, in commercial tendon‐driven systems, challenges remain, including tendon fatigue and bulkiness. Promising alternatives are magnetically actuated systems, offering contactless steering but limited forces. To overcome this, a miniaturized, locally actuated magnetic gripper with variable stiffness is presented. The gripper employs thin planar coils (75 μm) and a radially magnetized plunger, enabling local actuation and enhanced orientation control. The variable stiffness compliant mechanism made from shape‐memory polymer facilitates different gripping strategies. In its rigid state, pulsed pulling forces of 340 mN and continuous forces of 90 mN are achieved, exceeding the gripper weight by factors of 70 and 18, respectively. The soft state, with a fast response time of 20 ms, enables soft gripping of various targets, including moving ones and rat tissue samples. Demonstrating the applicability, contactless steering and target retrieval within a stomach phantom is showcased. This study introduces promising improvements to magnetically actuated grippers for surgical procedures, addressing key challenges in current designs.

Experimental Assessment of Predictive Current Control Applied to Induction Machine Drive Systems Operating Under Single-Phase Open-Circuit Fault


 Predictive Current Control (PCC) has been widely applied in several applications. However, the literature has not discussed its use as a fault tolerance control algorithm in induction drive systems. In this way, this paper discusses the PCC method in two faulttolerant squirrel-cage induction machine drive systems operating under single-phase open-circuit faults. PCC’s postfault performance is compared to Field Oriented Control (FOC) for different steady- and transient-state scenarios, analyzing harmonic distortion, torque ripple, and the transition from healthy to postfault operation. Also, experiments tested the robustness of postfault PCC to low-speed operation, parametric variation, and a step change in reference rotor speed, showing that PCC also presents fault-tolerant operation under these conditions.

Simultaneous Intra- and Intermolecular Singlet Fission in Bipentacene Macrocycle Aggregates.

Singlet fission (SF) is a process where a singlet state splits into two triplet states, which is essential for enhancing optoelectronic devices. Macrocyclic structures allow for precise control of chromophore orientation and facilitate singlet fission in solutions. However, the behavior of these structures in thin films, crucial for solid-state device optimization, remains underexplored. This study examines the aggregation and singlet fission processes of bipentacene macrocycles (BPc) in thin films using molecular dynamics simulations and electronic structure calculations. Findings indicate that BPc aggregates more rapidly with less chloroform, aligning parallel to the substrate. Intramolecular singlet fission (iSF) rates are rarely changed during evaporation, but the efficiency of intermolecular singlet fission (xSF) improves due to the increase in packing domains, suggesting that orderly crystal domains are not necessary for device efficiency. This opens avenues for varied device designs and traditional solution-based methods for optimal device development.

Synchronous Pitch and Yaw Orientation Control of a Twin Rotor MIMO System Using State Varying Gain Sliding Mode Control

Synchronous Pitch and Yaw Orientation Control of a Twin Rotor MIMO System Using State Varying Gain Sliding Mode Control

On-Surface Fabrication toward Polar 2D Macromolecular Crystals.

Polar 2D macromolecular structures have attracted significant attention because of their ferroelectricity and ferro-magnetism. However, it is challenging to synthesize them experimentally because dipoles or spins of these macromolecules tend to cancel each other. So far, there has been no successful strategy for assembling macromolecules in a unidirectional manner, achieving stereoregular polymerization on metal surfaces, and creating polar 2D polymer crystals. Recent progress in molecular assembly, on-surface polymer synthesis, and direct control of molecules using electric field applications provides an opportunity to develop such strategies. In this regard, we first review past studies on chiral and achiral molecular assembly, on-surface polymer synthesis, and orientation control of polar molecules. Then, we discuss our newly developed approach called "vectorial on-surface synthesis", which is based on "dynamic chirality" of compass precursors, stereoselective polymerization, and favorable interchain interactions originating from CH-π interactions. Finally, we conclude with a prospective outlook.

Simulation Study of Polyethylene Terephthalate Hydrolase Adsorption on Self-Assembled Monolayers.

Polyethylene terephthalate (PET) hydrolase, discovered in Ideonella sakaiensis (IsPETase), is a promising agent for the biodegradation of PET under mild reaction conditions, yet the thermal stability is poor. The efficient immobilization and orientation of IsPETase on different solid substrates are essential for its application. In this work, the combined parallel tempering Monte Carlo simulation with the all-atom molecular dynamics simulation approach was adopted to reveal the adsorption mechanism, orientation, and conformational changes of IsPETase adsorbed on charged self-assembled monolayers (SAMs), including COOH-SAM and NH2-SAM with different surface charge densities (SCDs). The results show that the protein adsorption orientation was determined not only by attraction interactions but also by repulsion interactions. IsPETase is adsorbed on the COOH-SAM surface with an "end-on" orientation, which favors the exposure of the catalyzed triplet to the solution. In addition, the entrance to the catalytic active center is larger on the COOH-SAM surface with a low SCD. This work reveals the controlled orientation and conformational information on IsPETase on charged surfaces at the atomistic level. This study would certainly promote our understanding of the mechanism of IsPETase adsorption and provide theoretical support for the design of substrates for IsPETase immobilization.

Assessing the Link Between General Causality Orientations and Problem Gambling, and the Mediational Role of Nonattachment, Greed, and Anhedonia.

Gambling is common in the US, yet nearly one in three players experience gambling-related problems. Using Self-Determination Theory, this study explores how three causality orientations-autonomous, controlled, and impersonal-affect the severity of problem gambling. The study further investigates the mediating roles of nonattachment, dispositional greed, and anhedonia to illuminate how these orientations relate to problem gambling. The data from 675 participants (59% male; Mean age = 40.4years, SD = 12.9) via Amazon's Mechanical Turk were collected following a screening procedure to identify at-risk players. Findings showed that dispositional greed mediated the impact of a controlled orientation on problem gambling severity, while anhedonia mediated the effect of impersonal orientation. Unexpectedly, nonattachment did not explain the effect of autonomous orientation on problem gambling, though a negative association was still observed. This research enhances understanding of how individual differences and causality orientations contribute to problem gambling behavior. The implications are discussed.

The Design and Implementation of a Phased Antenna Array System for LEO Satellite Communications.

LEO satellite constellations can provide a viable alternative to expand connectivity to remote, isolated geographical areas and complement existing IoT terrestrial communication infrastructures. This paper aims to improve LEO satellite communications by implementing a new phased antenna array system that can significantly improve the radio communication link's performance. By adjusting the progressive phase shift to each element of the antenna array system, the direction of the main radiation lobe of the phased antenna array system can be controlled with accuracy. As far as we know, it is the first time that a four-element, three-quarter wavelength phased antenna array system has been successfully realized with the intention of being optimized for implementation in LEO IoT satellite reception systems. The proposed system's high level of performance is confirmed by the measurements, which indicate effective control of the main radiation lobe orientation. The numerical analysis shows a maximum gain close to 12 dBi for about 42° elevation, a Half Power Beamwidth (HPBW) of 32° in the vertical plane, and 80° in the azimuth plane. The experimental measurement results at various main lobe orientation angles revealed an HPBW ranging from 76° to 87° in the azimuth plane and a maximum Front-to-Back ratio (F/B) of 14.5 dB.

Molecular Electronics: From Nanostructure Assembly to Device Integration.

Integrated electronics and optoelectronics based on organic semiconductors have attracted considerable interest in displays, photovoltaics, and biosensing owing to their designable electronic properties, solution processability, and flexibility. Miniaturization and integration of devices are growing trends in molecular electronics and optoelectronics for practical applications, which requires large-scale and versatile assembly strategies for patterning organic micro/nano-structures with simultaneously long-range order, pure orientation, and high resolution. Although various integration methods have been developed in past decades, molecular electronics still needs a versatile platform to avoid defects and disorders due to weak intermolecular interactions in organic materials. In this perspective, a roadmap of organic integration technologies in recent three decades is provided to review the history of molecular electronics. First, we highlight the importance of long-range-ordered molecular packing for achieving exotic electronic and photophysical properties. Second, we classify the strategies for large-scale integration of molecular electronics through the control of nucleation and crystallographic orientation, and evaluate them based on factors of resolution, crystallinity, orientation, scalability, and versatility. Third, we discuss the multifunctional devices and integrated circuits based on organic field-effect transistors (OFETs) and photodetectors. Finally, we explore future research directions and outlines the need for further development of molecular electronics, including assembly of doped organic semiconductors and heterostructures, biological interfaces in molecular electronics and integrated organic logics based on complementary FETs.

Uniaxial-Oriented Perovskite Films with Controllable Orientation.

Perovskite films with large crystal size, preferred orientation, and facile fabrication process, combining advantages of single-crystal and polycrystalline films, have gained considerable attention recently. However, there is little research on the facet properties of perovskite films. Here, (111)- and (001)-oriented perovskite films with bandgaps ranging from 1.53 to 1.77eV, and systematically investigated their orientation-dependent properties are achieved. The (111)-oriented films show electron-dominated traps and the (001)-oriented films show hole-dominated traps, which are related to their atomic arrangement at the surface. Compared with the (001)-oriented films, the (111)-oriented films exhibit lower work function and superior water/oxygen robustness. For the wide-bandgap films, the lattice of the (001)-oriented film provides an unobstructed passage for ion migration. Comparably, the (111)-oriented films exhibit suppressed ion migration and excellent phase stability. The optimized unencapsulated solar cells based on both (001) and (111) orientations show a similar high efficiency of ≈23%. The (111)-oriented solar cell exhibits excellent stability, maintaining 95% of its initial efficiency after 1500h maximum power point (MPP) tracking test, and 97% initial efficiency after 3000h aging in ambient conditions. This work paves the way for the rational design, controllable synthesis, and targeted optimization of uniaxial-oriented perovskite films for various electronic applications.

Design and experiment of Panax notoginseng root orientation transplanting device based on YOLOv5s.

Consistent root orientation is one of the important requirements of Panax notoginseng transplanting agronomy. In this paper, a Panax notoginseng orientation transplanting method based on machine vision technology and negative pressure adsorption principle was proposed. With the cut-main root of Panax notoginseng roots as the detection object, the YOLOv5s was used to establish a root feature detection model. A Panax notoginseng root orientation transplanting device was designed. The orientation control system identifies the root posture according to the detection results and controls the orientation actuator to adjust the root posture. The detection results show that the precision rate of the model was 94.2%, the recall rate was 92.0%, and the average detection precision was 94.9%. The Box-Behnken experiments were performed to investigate the effects of suction plate rotation speed, servo rotation speed and the angle between the camera and the orientation actuator(ACOA) on the orientation qualification rate and root drop rate. Response surface method and objective optimisation algorithm were used to analyse the experimental results. The optimal working parameters were suction plate rotation speed of 5.73 r/min, servo rotation speed of 0.86 r/s and ACOA of 35°. Under this condition, the orientation qualification rate and root drop rate of the actual experiment were 89.87% and 6.57%, respectively, which met the requirements of orientation transplanting for Panax notoginseng roots. The research method of this paper is helpful to solve the problem of orientation transplanting of other root crops.

The Effect of Musical Environments on Designers' Attention: Persistent Music Listening Interferes with Attention.

Research indicates that music can influence human cognitive functions. Diverse musical settings can affect alertness, orientation, and executive control of attention in various populations. Exploring the relationship between designers with highly creative thinking and music environments can provide new research perspectives for the cognitive field. A total of 94 students, consisting of 61 design majors and 33 non-design majors, completed the Attention Network Test (ANT) on a computer under three test environments: cheerful music, melancholic music, and silence. The study results indicated that the alerting network effect between the design professional group and the control group was marginally significant. However, there were no significant differences between the groups in the orienting subsystem and the executive control subsystem. Within the design professional group, the attentional network data indicated that participants showed improved performance in alerting and orienting attention in a music-free environment compared to cheerful and melancholic music environments (pa = 0.028, po = 0.008). Nevertheless, executive control attention did not show significant differences across the music environments. In conclusion, existing research confirms that designers are more susceptible to distraction from external stimuli; thus, music-free environments assist them in concentrating.

Janus microparticles-based targeted and spatially-controlled piezoelectric neural stimulation via low-intensity focused ultrasound

Electrical stimulation is a fundamental tool in studying neural circuits, treating neurological diseases, and advancing regenerative medicine. Injectable, free-standing piezoelectric particle systems have emerged as non-genetic and wireless alternatives for electrode-based tethered stimulation systems. However, achieving cell-specific and high-frequency piezoelectric neural stimulation remains challenging due to high-intensity thresholds, non-specific diffusion, and internalization of particles. Here, we develop cell-sized 20 μm-diameter silica-based piezoelectric magnetic Janus microparticles (PEMPs), enabling clinically-relevant high-frequency neural stimulation of primary neurons under low-intensity focused ultrasound. Owing to its functionally anisotropic design, half of the PEMP acts as a piezoelectric electrode via conjugated barium titanate nanoparticles to induce electrical stimulation, while the nickel-gold nanofilm-coated magnetic half provides spatial and orientational control on neural stimulation via external uniform rotating magnetic fields. Furthermore, surface functionalization with targeting antibodies enables cell-specific binding/targeting and stimulation of dopaminergic neurons. Taking advantage of such functionalities, the PEMP design offers unique features towards wireless neural stimulation for minimally invasive treatment of neurological diseases.

Enabling resonant ultrasound spectroscopy in extreme environments

Elastic moduli are fundamental thermodynamic susceptibilities that connect to thermodynamics, electronic structure, and mechanic properties. Thus, determining the changes of elastic moduli as a function of time or temperature is a powerful tool to study several thermodynamic and materials phenomena. Resonant Ultrasound Spectroscopy (RUS) determines elastic constants with high accuracy and precision from a single measurement of the mechanical resonances of a sample. Conventionally, the quantitative extraction of elastic moduli with RUS assumes free boundary conditions but lead to unstable positioning of the sample making it incompatible with extreme environments like high magnetic fields. In practice, even holding the sample produces contact forces that deviate from free-boundary conditions shifting resonant frequencies. In this talk, we show that, we can reduce the free-boundary conditions (by gluing/adhering the sample to the transducer), while still being able to obtain the full elastic tensor by a simple model of the sample-transducer interaction. This means elastic constants can be determined to within the uncertainty of conventional RUS, but with significant improvements in sample stability and control of sample orientation. We show the results of studying of several magnetic and structural phase-transitions using this new method.

Orientation control of multiple single crystal blades using a novel high-throughput mold via seeding-grain selection technique

As the increasing demand for high temperature performance of the Ni-based single crystal blades, the orientation consistency of the blades has become more and more important. In this work, a novel high-throughput mold capable of producing four single crystal blades with exactly the same orientation was proposed. The effects of the two important parameters as connector height and blade placement angle on single crystal growth were investigated by ProCAST simulation. The results showed that the 90° connector with a height of 50 mm could obtain the most appropriate temperature gradient for the production of single crystal blades, and when the blades were placed at 120° and 270°, the flattest liquid isotherm could be obtained. However, due to the difference in the distance of the nucleation points from the mold center and the direction where the thin edge of the blade platform faced, the blade placed at 120° had a larger platform area occupied by the stray grains. Therefore, the structure of this mold was determined by using a 90° connector and placing blades at 270°. At last, using this mold, four single crystal blades with the same three-dimensional orientation and no stray grains were successfully produced. These results fully demonstrated the feasibility of this novel mold and also provided ideas for using simulation methods to guide the design of the new mold structure.

The role of magnetic anisotropy in the magnetoresistance of Cr2O3/Al2O3 thin film antiferromagnets

The magnetic states of antiferromagnetic insulating thin films are a promising medium for information storage, but characterization of these states has proven to be challenging. One approach is via magnetotransport measurements in an adjacent heavy metal layer. To this end, we synthesized and characterized a series of Cr2O3 films and bilayers on Al2O3 substrates with three different orientations: m-plane, a-plane, and c-plane. X-ray diffraction results demonstrated orientation control of the Cr2O3 thin film, with m-plane films displaying a higher degree of mosaic spread than the a- and c-plane films. Reciprocal space maps showed that the films are mostly relaxed, although there was a small and different degree of strain in each orientation. The m-plane films were under 2% compressive strain, the a-plane film was under 0.5% compressive strain, and the c-plane film was completely relaxed to bulk values. To probe the magnetic state of the films, we measured the angular dependent magnetoresistance of Cr2O3/Pt bilayers for each orientation. We found a nontrivial temperature dependence of the sign of the magnetoresistance, pointing to the complex interplay between the exchange and anisotropy energies that vary with orientation. We propose that strain and mosaic spread may contribute to a difference in magnetic anisotropies among the samples and the resulting temperature dependence of the magnetoresistance. This work demonstrates the importance of considering the competition between antiferromagnetic exchange and magnetic anisotropy when storing information in the spin state of an antiferromagnetic insulator.