Directional Slot Research Articles

Strategies for Printing Ultra-Thin and Variable Width Lithium Foil

The commercial success of rechargeable lithium-related batteries in electronic devices since the 1990s has been remarkable. Technologies in the field continue to develop to make batteries safer, longer lasting, and more powerful. Emerging lithium-ion battery technologies such as solid-state batteries or high-silicon anode materials utilize, for example, ultra-thin lithium metal foil due to lithium metal high specific capacity (3860 mA h g-1), however; traditional thin lithium foil manufacturing methods have proven challenging at scale due to metal reactivity, poor foil tensile strength, and safety concerns. Additionally, lithium metal foil is needed in a variety of thicknesses, widths, and surface characteristics, which are all crucial for advancing lithium metal based batteries. Fortunately, it can be done via industry standard technologies when using LIOVIX®, Printable Lithium Technology.LIOVIX formulation has been coated using direct slot die technology at the benchtop scale and tension web slot die technology at the Roll-to-Roll (R2R) scale. Slot die technology facilitates two major elements of this process; particles larger than the theoretical wet film thickness can be deposited, and also the material can be shipped, delivered, and mixed without exposing lithium to air until it leaves the slot die head. This approach allowed us to achieve a uniform coating with heights ranging from 7 µm to 30 µm at a variety of coating widths. This has been done at the benchtop level at speeds up to 200 mm s-1 while maintaining a uniform coating on a copper substrate. R2R coating has done via a tension web coater, with similar theoretical wet film thickness. Specifically, the application of LIOVIX as a coating is particularly noteworthy for offering a strategic advantage in large scale manufacturing while maximizing the electrochemical performance.LIOVIX formulation enables the R2R production of lithium foil materials, and using a pre-metering system, the coating can be reliably produced at a variety of areal capacity targets.

Evaluation of the resection plane three-dimensional positional accuracy using a resection guide directional guidance slot; a randomized clinical trial

AimThe study was performed to compare the mandibular resection guide with a directional guidance slot with the conventional guide regarding three-dimensional positional accuracy.Materials and methodsTwenty-six patients with lateral segmental mandibular defects were selected, and randomly allocated into two groups. All defects were managed with preoperative virtual surgical planning. Resection in the test group was conducted using a resection guide with a directional guidance slot, while a conventional resection guide design was utilized in the control group. The linear and angular deviation of the osteotomy planes was analyzed for both groups, along with the accuracy of the insertion of the reconstruction bone block in the resected defect. Data were documented, absolute deviation was calculated, statistical analysis was performed and significance was set at the 5% level.ResultsThe cases conducted with a directional guidance templet reported a statistically significant difference when compared to the conventional edge-cutting guide regarding the linear and angular spatial osteotomy plane position (P < 0.001). The defect span analysis reported excellent levels of agreement in both groups (ICC = 1.00, ICC = 0.995), however, the difference between the groups was statistically significant (P < 0.001).ConclusionThe study demonstrated the enhanced positional accuracy of the resection plane and reconstruction block placement when a directional slot is incorporated in the computer-generated resection guide.

Cooling and dynamic performance of electric vehicle traction motor adopting direct slot cooling method

Heat loss in an electric vehicle traction motor can be an important cause of insulation breakdown in coil winding and demagnetization of rotor magnets, resulting in a gradual or permanent malfunction of the motor. Thus, a motor cooling technique that immediately removes a large amount of heat released under extremely tough driving conditions is needed. In this study, the cooling and dynamic performances of two motors adopting the direct slot cooling (DSC) and water jacket cooling (WJC) methods were tested. The coolant in the DSC model directly cools the main heat source of the coil winding using the open slot of a motor stator as the cooling channel. Through thermal and electromagnetic simulations, the motor maximum and average motor temperatures under constant-current and real-driving conditions, marginal current density in a given coolant pumping power, and maximum torque and power of both motors are presented in detail.

Review on Thermal Behavior and Cooling Aspects of Axial Flux Permanent Magnet Motors–A Mechanical Approach

With the increasing demand for high-energy density motors for applications such as electric vehicles and aircraft propulsion, axial flux permanent magnet motors are promising. However, utmost care should be taken when designing an axial flux permanent magnet motor with a higher torque density because of thermal effects. To enhance the reliability and overall performance of a motor, efficient thermal management is important, because the torque density is restricted by maximum temperature. Therefore, this study comprehensively reviews different techniques used for the thermal modeling of motors. Computational fluid dynamics, the lumped parameter method, and finite element analysis were used to calculate the total heat transfer inside the motor. Various heat enhancement techniques for an axial flux permanent magnet motor have been presented, including core cooling (water jacket cooling, air cooling, and oil cooling) and winding cooling (direct slot cooling, end winding cooling, and fins). Finally, two case studies of an 8kW AFPM motor and a 65kW AFPM motor with a cooling arrangement are discussed.

Design procedure and optimisation methodology of permanent magnet synchronous machines with direct slot cooling for aviation electrification

AbstractElectric machines are widely employed in a variety of sectors, including automotive and aerospace industry. With the rising trend towards electrification in aviation, electric machines with increased power density and efficiency are becoming key enabling technologies, requiring the development of innovative design procedures. In this study, a preliminary design procedure for Surface Mounted Permanent Magnet Synchronous Machines (SPMSMs) intensively cooled by means of oil channels placed in the stator slots is proposed. The analytical derivation of SPMSM sizing equations, including the sub‐domain model and optimisation algorithm will be reported in detail. Indeed, both the electromagnetic and thermal equations of the machine are considered for the derivation of the sizing tool. As a result, the latter allows to capture variation of the machine design not only in terms of mechanical demands, such as power and speed, but also in terms of coolant characteristics, and can be effectively employed to perform trade‐off studies at a preliminary design stage. The proposed design tool will be used for a specific case study: The design of a high‐speed machine for an aerospace hydraulic actuator. The accuracy of the proposed design tool is validated for different parameters by comparing the results to experimental measurements performed on an existing 8‐pole 9‐slot prototype SPMSM.

Enhancement of cooling performance in traction motor of electric vehicle using direct slot cooling method

• DSC(Direct Slot Cooling) has been proposed for high-power and high-torque traction motors. • To evaluate the performance of DSC, we compared it with existing motor-cooling technologies, such as water-jacket, end-tip and channel coolings. • DSC enables a 66% and 94% increase in the applied current density compared to that of water-jacket cooling and end-tip cooling, respectively. • By adopting the DSC model, the winding maximum temperature did not exceed 90 °C in the highway driving mode, even when a high current density of 70 A/mm2 was momentarily applied. The torque of a traction motor for electric vehicles is directly proportional to the electric current applied to the motor winding. Since a power increment is directly linked with an increase in torque, traction motors with high electric current are needed to enhance the dynamic performance of electric vehicles. However, heat loss in the winding, which is proportional to the square of the applied electric current, may cause insulation breakdown in the winding or demagnetisation of permanent magnets in the rotor. In this study, we employed direct slot cooling (DSC) to directly cool motor windings, which are the main heat source in a motor, with cooling fluids. To evaluate the performance of DSC, we compared it with existing motor-cooling technologies, such as water-jacket, end-tip and channel cooling. The performances of the cooling methods were compared based on the change in the pumping power of the cooling fluid and the winding current density. Under two real road driving modes (urban dynamometer and highway driving modes), we compared the change in temperature with time in the traction motor of a compact car with the various cooling methods. The proposed DSC model showed good cooling performance; the winding maximum temperature did not exceed 90 °C in the highway driving mode, even when a high current density of 70 A/mm2 was momentarily applied.

Design of highly directive slot antenna using metamaterial structure under optimal condition

In this article, a highly directive slot antenna design using a parallel incident magnetic metamaterial (MTM) structure has been presented. A split ring resonator (SRR) structure having mu near-zero and epsilon very large with low impedance behavior is employed to enhance the directivity of the antenna. In the proposed optimized design, four-MTM slabs with an array of 2 × 2 SRR unit cell have been placed perpendicularly over the slot antenna to enhance the directivity. The thickness of utilized MTM slab in the vertical direction is under the optimal condition, which is highly desired to obtain better improvement in directivity. In spite of directivity enhancement of about 6 dB, antenna miniaturization of 11.4% is also obtained due to the loading effect of the MTM slab. The proposed directivity enhancement approach of the slot antenna is established by simulation and verified by measurements. It is perceived from both measured and simulated results that over the whole working band, a significant directivity enhancement is sustained along with reduced backward radiation compared to the unloaded slot.

Performance of defected ground structure with miniaturized microstrip patch antenna using RMPA substrate material

Abstract A parallel structural antenna with the acts slot configuration is indicated for process of 5G wireless technology. The direct slot configuration defined within the patch antenna drives the 5G mid band and twin band frequency reaction in the frequency location without the conditions. Next, a 2-D Double Periodic Electronic Band (EBG) shape is carried out below the metal ground aircraft to request an extended impedance bandwidth for RMPA Materials. The slot duration and feature changed into designed for an impedance bandwidth of 12.49% and 4.49% at three pass band frequencies of 532 GHz and, 835 GHz respectively. Simulated with measured gain and reflection coefficient of correct settlement for bending bandwidths. The antenna array length is 33.5 mm × 33.5 mm. The antenna modified structure and the experimental effects were compared with all the other existing systems. The proposed antenna, which makes use of the EBG structure, suggests pics and excessive sensitivity steady with a massive impedance bandwidth, meeting the necessities of the IoT software program supplied with the resource of 5G technology.

Compact broadband slot‐based MIMO antenna array for vehicular environment

AbstractThis article presents the design, fabrication, and testing of a broadband directional slot antenna and its application in a vehicular environment. The proposed antenna consists of a slot antenna fed by a simple microstrip line. Broadband impedance matching is achieved by replacing the conventional microstrip line with a modified microstrip line. The modified microstrip line consists of a microstrip line terminated with an impedance transformer and a square patch. The proposed antenna offers 76.9% bandwidth centered around 4.8 GHz covering most of the communication applications between 3 and 6.75 GHz. Furthermore, the antenna's radiation pattern is shaped to obtain the desired directional characteristics using a simple reflector and array of via holes. The typical gain enhancement is 2.45 dBi at 5 GHz. This gain enhanced slot antenna is further used to construct the four‐element MIMO antenna. The proposed MIMO antenna configuration offers omnidirectional coverage with realized antenna gain greater than 6 dBi making the antenna more suitable for the vehicular environment. The prototype antenna and the MIMO array are fabricated and measurement results are presented. The measurement results are in good agreement with the simulation results.

Cooling Technologies for High Power Density Electrical Machines for Aviation Applications

This paper is aimed at giving an overview of possible cooling technologies for electrical machines and their assessment for aviation applications, e.g., fan or propeller drives. The most important demand for aircraft is the minimization of the drive system weight comprising electrical machine, power electronics, and the cooling system. The potential of aluminum winding an overview about several cooling technologies with the Rankine or Brayton cycle or utilizing the phase change of the cooling fluid is given. As an alternative approach, the cooling structure inside the machine is studied. A very interesting potential was discovered with direct slot cooling (DSC) removing the heat where it is produced and, thus, simplifying the cooling system effort and its weight. Since it is one of the most promising approaches, this cooling method is studied in depth. Furthermore, it can also be combined with one of the cooling technologies discussed above.

Dual-Band Directional Slot Antenna for Wi-Fi Application

A directional slot antenna with a squared arch structure for Wi-Fi applications is proposed in this communication. In general, one antenna can hardly obtain a nonsplitting and relatively consistent radiation beam in both the 2.4 and 5 GHz bands. A relatively consistent horizontal beamwidth in the dual bands is desired to maintain the same sector signal coverage and avoid interfering with adjacent sectors to maximize the data transmission in usage scenarios such as a sports stadium and warehouse. With a squared arch design, the proposed slot antenna can keep the H-plane beamwidth relatively the same in the dual bands. The slot antenna achieves good matching in both the 2.4 (2.4–2.5 GHz) and 5 GHz (4.9–5.9 GHz) bands, and good vertical polarization. An expression describing the condition of generating a nonsplitting beam is derived as a function of the source spacing, and can be used to guide the arch design. Finally, the proposed slot antenna with the squared arch structure is validated by both simulations and measurements of a prototype.

Characterization of bedload discharge in bores and very unsteady flows in an ephemeral channel

Bedload flux under steady flow conditions is calculated by a multitude of available methods and equations. Yet, very little is known about the effect of very unsteady flows, such as flash floods and specifically bores, on bedload flux. The unpredictable nature of the floods together with many logistic difficulties and safety issues in monitoring explain this gap in knowledge. Global climate change may increase flood event occurrence, making their understanding even more crucial. The methodology of our study is based on automatically monitoring bedload flux (Reid slot samplers). Automation allowed high frequency monitoring of hydraulic parameters and bedload flux. Added novelty includes pipe and plate microphones for capturing acoustic signals of bedload sediments and 3-D velocimetry for characterizing turbulence. Alerting sensors and cellular data transmission enabled onsite presence upon bore arrival. Calibration between the acoustic indirect sensors and the direct slot samplers allows determination of bedload flux at a frequency of 1 Hz. Analyses of flood events indicate an increase in turbulent kinetic energy, instantaneous vertical velocities, shear stress and bedload flux during the rising limb within the first two minutes after bore arrival. This has implications for the likely destabilization of the channel bed and for bedload transport after passage of the bore and during subsequent, less unsteady flows.

Experimental Study on Quasi‐Static Pressure of Slot Hydraulic Blasting

Air is commonly used as the noncoupling borehole medium in directional slot blasting where the quasi‐static pressure is small, the energy utilization rate of the explosive is low, and the breaking efficiency of the coal‐rock mass is not high. This study investigates the effect of quasi‐static pressure on crack propagation in closed‐field blasting. Crack length propagation in the quasi‐static pressure stage accounts for more than 60% of the total crack length. Water is therefore proposed as the noncoupling medium of the slotting borehole to increase the quasi‐static pressure. A series of experiments was performed to investigate and compare quasi‐static pressures generated using noncoupled water‐medium blasting and noncoupled air‐medium blasting. The experimental results show that the quasi‐static pressure is 37–46 times larger in water‐medium blasting than in the air‐medium case. The experimental measurements show good agreement with theoretical analysis. The results show that the energy utilization rate of the explosives in the hydraulic slotting blasting is high with a notable energy storage effect, and that the fracturing range can be significantly increased. Additionally, fracture by directional blasting using this approach can be more controllable.

A Compact Directional Slot Antenna and Its Application in MIMO Array

In this communication, a new design for the microstrip-fed slot antenna with a directive radiation pattern for WLAN/WiMAX application is presented. By utilizing a two-element array topology, a unidirectional radiation pattern is obtained. Without any directors and reflectors, the proposed slot antenna shows advantages in terms of compact size and high front-to-back gain ratio in the azimuthal plane. Four directional slot antennas are then placed in a square loop array to obtain nearly orthogonal patterns. Thus, a compact multiple input multiple output array with high isolation among those four elements is achieved. Simulated and measured results are presented to validate the practicality of the proposed antenna structures.

Compact Broadband Directive Slot Antenna Loaded With Cavities and Single and Double Layers of Metasurfaces

In this paper, a compact wideband directive metasurface (MS)-based antenna is proposed. A pair of edge-fed slots, assisted by a fictitious short, is used to excite the MS layer which is made up of a periodic arrangement of rectangular loop-based unit cells along both the $x$ - and $y$ -directions. The proposed MS-based slot antenna is compact and provides good matching over the entire bandwidth with a broadside radiation pattern. A metallic cavity and an artificial magnetic conductor-based cavity are integrated on the MS-based antenna to reduce its backward radiation. Finally, a pair of edge-fed slot antennas combined with two layers of MSs having compact ground plane area of 1.04 $\lambda _{0}^{2}$ ( $\lambda _{0}$ is the operating wavelength in free space) is proposed for the improvement of gain, bandwidth, and forward radiation. The overall antenna has a low profile of 0.05 $\lambda _{0}$ . The proposed configuration shows a 21% measured bandwidth with an average gain of 9.6 dB over its bandwidth. Over its bandwidth, the antenna efficiency is >89%. The design is validated by a full-wave simulation study followed by the experimental verification.

Design of Compact and High Directive Slot Antennas Using Grounded Metamaterial Slab

In this letter, a simple and compact approach for directivity enhancement of slot antenna using a grounded metamaterial slab is proposed. This approach has been applied in two different configurations. In the first configuration, two dielectric layers are used for designing antenna and metamaterial slab. Despite the directivity enhancement, an improved bandwidth of about 10.74% is obtained for this configuration. It is also shown that, over the whole working band, a significant broadside directivity improvement is maintained compared to the unloaded slot. In the second configuration, only a single layer of dielectric is used for designing both antenna and metamaterial slab. Thus, in this case, the total thickness of the loaded antenna is noticeably reduced to 0.5 mm, or 0.014 λ0 at resonance.

Circularly Polarized One-Sided Directional Slot Antenna With Reflector Metal for 5.8-GHz DSRC Operations

This letter presents a new design for a circularly polarized one-sided directional slot antenna with reflector metal for 5.8-GHz dedicated short-range communications (DSRC) operations. Our proposed antenna was composed of a slot antenna, additional slots, a floating metal layer, and reflector metal. By optimizing the lengths and widths of the slots in the two orthogonal directions, circularly polarized radiation was generated. In order to improve the antenna gain, some slots were attached on the top metal layer, and a floating metal layer was attached to the bottom of the antenna. Moreover, an additional dielectric substrate and reflector metal layer were connected to the back of the antenna. The total antenna size including the reflector metal layer was 22.6 × 22.6 × 6.926 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Our proposed antenna was fabricated on an FR4 substrate. The measured impedance bandwidth was 760 MHz from 5.82 to 6.58 GHz, and the measured circularly polarized gain was 4.59 dBic.

A Highly Directive Slot Antenna With Sidewall Corrugated Structure

We present a high-gain and low-profile dual-band surface-wave antenna based on a corrugated conducting plate with sidewall, in which a subwavelength aperture is made on the corrugated conducting plate. Introduction of the sidewall modulates the field of the surface wave above the corrugated plate. It makes a strong electric field appear at the center of the corrugated plate and suppresses the lateral radiation, thereby improving the radiation performance significantly. The transverse size of the corrugated plate can also be reduced effectively by the employment of sidewall. Numerical simulations and experimental results show that the gains of antenna at the lower and upper operation bands increase significantly, which have very good agreements, validating the performance of the proposed surface-wave antenna.

Transitive be perfect : An experimental study of Canadian English

AbstractThis article investigates exemplars of the transitivebeperfect in Canadian English, such asI am done dinnerandI am finished my homework. I report on an experimental study of acceptability judgments of this construction, given by speakers of Canadian English primarily recruited from the Calgary area. I claim that the construction [be doneNP] is characterized by preference for the animacy of the subject, preference for definiteness of the direct object, open-endedness of the direct object slot, and limited variability of the participle. I conclude that [be doneNP] is a partially schematic construction that is close to a “prefab”.

Directional Blasting Demolition Technology of 150m-High Reinforced Concrete Chimney and 75m Cooling Tower

This paper describes the successful experience of the directional control blasting demolition of 150m-high reinforced concrete chimney and 75m cooling tower of Shizuishan Power Plant in Ningxia. It emphatically describes the pretreatment measures, blasting cut shape and size, blasting parameters, detonating network and blasting safety technology of the directional window, oriented window and load reducing slot. This paper provides the method for opening the overlarge arch oriented window, opening the special-shape load reducing slot and dense mesh safety net cross-multilayer coverage as well as comprehensive protection method for anti-flyrock splash and vibration reduction. Especially, the blast holes for opening the special-shape load reducing slot and the herringbone column are centralized at the bottom and top, which not only reduces the drilling workload, but also reduces the maximum detonating explosive amount of single section, and also reduces the safety protection workload.