Wiper Arm Research Articles

The development of a modular and open-source multi-head 3D bioprinter for fabricating complex structures

Various 3D bioprinting techniques have been introduced and developed to fabricate biomimetic constructs based on biomaterials or cell-laden bioinks to create functionally engineered tissues or organs for tissue engineering applications. However, single-biomaterial printing techniques often fail to replicate the intricate compositions and diversity found in native tissues. Multi-bioinks or multi-biomaterials in bioprinting can be utilized through either a single printhead or multiple separate printheads. However, the cost of commercially available multi-heads for bioprinting is prohibitively high, hindering their application in tissue engineering endeavors. Additionally, each bioink or biomaterial possesses unique printing characteristics that are best suited for specific printing techniques. The current study presents the development of a modular and cost-effective dual-head position bioprinter based on an open-source approach using Marlin firmware. The highlighted features of the 3D bioprinter include the use of various power sources such as compressed air and electricity for the printheads, the integration of a movable printhead mechanism with a wiper arm to prevent collisions with large printed samples during printing, a printhead adapter, as well as nozzle kits designed in a modular form for easy replacement for specific bio-applications. Therefore, despite the presence of two positions to mount the printheads, the custom-designed bioprinter exhibits the capability to flexibly accommodate four distinct printhead modules and three modular nozzle kits to print various biomaterials, such as polycaprolactone (PCL) and its composites with sodium alginate (SA), tricalcium phosphate (TCP) and hydrogel mixtures including SA, gelatin (GL), and k-carrageenan (κ-Carr). Complex tissue scaffolds were successfully fabricated using multi-biomaterials to showcase the versatility of the bioprinter, thereby demonstrating its potential for a wide range of tissue engineering applications.

Improvement of Flight Safety on Configuration Change of Rotorcraft Wiper Arm

Improvement of Flight Safety on Configuration Change of Rotorcraft Wiper Arm

Clamping performance of fastener in windshield wiper assembly using theoretical and experimental methods

Improper clamping of wiper arms can cause problems in the operation of the wiper. An excessive clamping force can cause damage to the wiper arm head. On the other hand, an insufficient clamping force can cause self-loosening of the nut. Given the lack of direct research on the clamping force of the fastener in wiper assembly, this study verifies the existing clamping performance of the fastener in windshield wiper assembly by theoretical and experimental methods. The theoretical calculation results show that all the clamping performance are satisfied under the general snow load condition. However, under the critical load condition, maximum assembly preload and safety margin against slipping are in disagreement with the standard values. This problem is solved by increasing the strength grade of the bolt. The experimental results show a reducing tendency of the clamping force during the snow durability test. However, this reducing clamping force during the 60,000 test cycles is acceptable. In the case of nut reusing more than two times possibly cause a problem of its loosening because of insufficient clamping force. Therefore, it is recommended that the nut should not be reused more than two times.

About the Friction of the Wiper Windscreen Contact

In order to study the influence parameters for the wiper-windscreen friction, a test system was built, using an assembly of a car plane auto rear window glass, with the electrical motor, the wiper mechanism and also a wiper with a modified arm (by inserting a transducer to measure the friction force, based on tensometric strain gauges). Also on the wiper arm, on the opposite side of the arm/blade connection (located approximatelly at the middle of the blade length) a loading system was mounted. Different loading forces can be applied to the blade contact by gravity by simple changing the mass placed on this system. A large number of experiments were performed for different combinations of the values for the blade oscillating period and for the normal force in dry and wetted conditions for the blade-windscreen contact. The obtained results, reveal a direct correlation of the friction force with the load mass and with the relative speed in the contact (blade moving period). A higher friction occurs for the dry contact. This force has a higher increasing tendency for this contact than for the wetted contact when a stabilisation tendency of the friction force occurs.

Design of Locomotive Wiper Fuzzy Control System

In order to optimize synchronization of wiper arm, a locomotive wiper controller of PWM and Fuzzy PID controller are proposed. The PWM controller is mainly designed of input control circuit, a central control unit, DC wiper motor pulse width modulation control and drive circuit, the motor stops the braking circuit, single-speed wiper motor of permanent magnet DC, etc. It can realize the high speed, low speed, intermission, stop function of wiper. The controller has values of stable performance, low noise, simple structure, etc. In locomotive wiper controller, Fuzzy PID controller combines the advantages of Fuzzy controller and PID controller, that it can achieve fast response, small overshoot. Fuzzy PID can also ensure the steady-state accuracy of the system, and the control performance is better than PID control and fuzzy control.

Continuous rotatable electrical feedthrough

A rotatable electrical feedthrough, maintaining continuous contact (as opposed to a wiper arm), is described. The connector takes up rotations of at least 270° by means of a compact clock-spring arrangement.

Duration of Afterimage Disability After Viewing Simulated Sun Reflections

A scene was simulated of an automobile driver's view through his windshield. It contained a roadway, an identification target consisting of a Landolt C in various orientations on the road 96 m ahead, and a glare reflection of the sun arising from the direction of the driver's windshield wiper arm. The product of luminance times area of each of the four glare sources employed was about 0.1 of the maximum implied in the Federal Safety Standards. The target required a visual acuity of 20/40 on the Snellen scale, equal to that imposed by driver license requirements. After being exposed for realistic intervals while looking directly at the glare source, the duration of the interval required by thirty-five observers for identification of the target orientation was measured. Averages showed that the increase of identification time over that required after no glare exposure varied from 0.8 sec to 2.7 sec. Reduction of apparent area of the glare source reduced afterimage disability more than did reduction of intensity.

Instrument servomechanisms with backlash, coulomb friction, and stiction

AN INSTRUMENT servomechanism is normally thought of as a small positioning device with low power consumption. A typical block diagram is shown in Fig. 1. A gear ratio of 1 to 1 is used in this paper for convenience. The load is shown as an inertia with coulomb friction but no viscous friction. It is further assumed that JL = 0. This might correspond to the common case in which the output member is just the wiper arm of a potentiometer. When there is backlash in the gear train the following sequence of events is normal. The motor drives (with backlash taken up), reducing the error: as the motor velocity decreases the load velocity also decreases, and continuous mechanical contact is maintained because JL ? 0, and the coluomb friction C provides adequate drag on the output. When the motor velocity becomes zero, the load velocity also becomes zero. If the error is not zero, the motor reverses but the load does not move because of the backlash. Thus, the error does not change and the motor is driven open-loop with a constant driving torque, or voltage, until the backlash is taken up. The load is then ?picked up? by the drive and both the output velocity and the error rate jump from zero to the instantaneous drive shaft velocity. This sequence is usually repeated a number of times.