Locked Mechanism Research Articles

Narrow linewidth fiber laser using compound-ring cavity filter and self-injection locked mechanism

Narrow linewidth erbium-doped fiber lasers (EDFLs) hold in significant potential optical fiber sensing, wavelength multiplexing transmission, and optical fiber communication. However, many EDFLs produced outputs with linewidth in several kHz level. Therefore, a high optical signal-to-noise ratio (OSNR), narrow linewidth single-longitudinal-mode (SLM) EDFL was proposed and investigated in this work. The EDFL utilized a combination of compound-ring cavity filter and a self-injection locked mechanism to generate a stable SLM output with an OSNR greater than 72 dB. The maximum wavelength drift and maximum peak power fluctuation over 60 min were maintained at low values of 0.0041 nm and 0.16 dB. Moreover, a narrow linewidth of 1.82 kHz at a measuring time of 0.002 s was realized. Furthermore, the research also investigated output power variations with different pump powers, relaxation oscillation, and the dependence of output central wavelength on the axial strain.

Self−Mode−Locked 2−μm GaSb−Based Optically Pumped Semiconductor Disk Laser

We present a mode−locked GaSb−based optically pumped semiconductor disk laser operating at 2 µm based on the self−mode−locked mechanism. Using the delay differential equation model, we discuss the influence of cavity length on the stability of self−mode−locking and design a Z−shaped long cavity for self−mode−locking. Employing an aperture and an F−P etalon in the cavity length of ~365 mm, we obtain stable self−mode−locking at a center wavelength of 2034.5 nm, with a pulse duration of 255.48 ps and average output power of 173 mW at a repetition rate of 404 MHz.

Dynamic Modeling and Simulation of a Parallel Locking Mechanism

Aiming at the locking problem of the mechanism in face-to-face contact, a kind of parallel mechanical locking device is designed, which can make the locked surface self-locking even when the locking hydraulic system fails, thus ensuring the safety and reliability of the locked mechanism. Through theoretical analysis and dynamic simulation of ADAMS software, the self-locking function of the device is verified and the self-locking Angle is calculated. Meanwhile, considering that the locking device may act as a “resonator” and cause secondary excitation to the locked device, which affects the vibration characteristics of the locked system, the mode analysis of the locking device is done by using ABAQUS software, and the feasibility of the locking device for the locked mechanism excited by low frequency is proved.

Adjustable buttons for ACL graft cortical fixation partially fail with cyclic loading and unloading.

Despite good initial pullout strength, it is unclear whether adjustable button (AB) devices for anterior cruciate ligament (ACL) soft-tissue graft fixation, which are based on the Chinese finger trap technique, resist cyclic loading. Furthermore, they have never been tested in a cyclic protocol including complete unloading. It was hypothesized, that the displacement of AB devices with the Chinese finger trap technique would be greater than that of continuous suture loop devices and other available AB mechanisms in a cyclic loading with complete unloading protocol. ACL reconstruction was performed in a porcine knee model using three different types of cortical fixation devices: two different AB devices that use the Chinese finger trap design, one AB device that uses a locked suture loop mechanism and two different continuous loop devices as control groups (n = 40). Specimens were mounted in a material-testing machine (Instron Inc.) that permitted 2500 loading and complete unloading cycles to a maximum of 250N, as well as continuous elongation recording. A one-way ANOVA was performed for statistical analysis. The displacement of ABs with a Chinese finger trap loop (mean 8.1; SD 1.5mm and mean 6.1; SD 1.4mm) was significantly greater than that of AB with a locked suture loop (mean 4.7; SD 1.0mm; p < 0.05) and devices with a continuous loop (mean 4.1; SD 0.5mm and mean 4.4, SD 0.3mm; p < 0.01). No significant differences were detected between the ABs with a locked suture loop and the continuous loops. Cyclic loading and unloading of AB using the Chinese finger trap technique leads to significantly greater construct lengthening compared with other devices. Complete unloading of the ACL is very likely to occur during rehabilitation after ACL reconstruction. Lengthening of the AB device due to cyclic loading might be a potential mode of failure of the ACL graft fixation. Therefore, when using an AB femoral fixation technique, a locked suture loop design or a careful rehabilitation protocol should be considered.

Development of New All-Optical Signal Regeneration Technique

All-optical signal regeneration have been the active research area since last decade due to evolution of nonlinear optical signal processing. Existing all-optical signal regeneration techniques are agitated in producing low Bit Error Rate (BER) of 10−10 at below than −10 dBm power received. In this paper, a new all-optical signal regeneration technique is developed by using phase sensitive amplification and designed optical phase locked signal mechanism. The developed all-optical signal regeneration technique is tested for different 10 Gb/s Differential Phase Shift Keying degraded signals. It is determined that the designed all-optical signal regeneration technique is able to provide signal regeneration with noise mitigation for degraded signals. It is analyzed that overall, for all degraded test signals, average BER of 10−13 is achieved at received power of −14 dBm. The designed technique will be helpful to enhance the performance of existing signal regeneration systems in the presence of severe noise by providing minimum BER at low received power.

A Tool Holder for Clamping Cutting Inserts Used for Turning in a Metal Cutting Operation

Metalworking industry is looking for increase in productivity and maintaining costs per part. One of the most effective methods is the drastic increase of cutting speed by use of Polycrystalline Cubic Boron Nitride (PCBN). The challenge in cast iron machining with ISO/ANSI inserts are high tooling costs and insufficient stability of the insert due to form locked clamping mechanism. The paper presents Beyond shield: an innovative clamping mechanism which provides better rigidity and less movement of the insert, combining with a new designed PCBN inserts shape which results in lower grinding, lower manufacturing time and eventually lower cost. Video abstract [Display omitted]

Characterization of 60 GHz Multi Quantum well passively mode-locked laser under optical self-injection locking

The quality and pulse compression of the 60GHz millimeter wave signals generated by 750μm long InAlGaAs Multi Quantum Well (MQW) passively mode locked laser under free running and optical self-injection locked conditions are experimentally characterized in terms of longitudinal modes under certain bias currents that range from 24mA to 90mA. Initially, the MQW laser is characterized in free running condition with no external injection. The measurements reflect that the free spectral range of laser under test is around 61GHz and exhibit more than 22 lasing modes. The laser is then integrated into low phase noise self-injection locking oscillator by feeding a part of output RF signal back into the laser cavity to enhance passive mode locking. By doing so the microwave line width of our laser is reduced from 900kHz to 24kHz with significant increase in output of resultant beat tones which exhibits strong passive mode locking. This is the first time that the free running microwave line width of MQW laser is reduced up to this level. It is evident from our experimental investigation that as we increase the power and phase correlation between different longitudinal modes inside laser cavity through optical self-injection, the strength of the passively mode locked mechanism is significantly increased and the phase noise of radio frequency signal is drastically reduced.

Research on the Folding and Deploying Mechanism with Analysis of Frictional Coefficient of Steel and Aerodynamic Resistance

In this article the folding and deploying mechanism is researched, the equivalent dynamical model is built, and the configuration of the folding and deploying mechanism is designed including the folding mechanism, the deploying mechanism and the locked mechanism. This paper obtains the athletic rule of folding and deploying mechanism, then analyses the dynamic time of the folding and deploying mechanism and the reliability of the locked mechanism, also analyses of frictional coefficient of the steel and aerodynamic resistance of the mechanics.

Characterization of 60 GHz multi quantum well passively mode-locked laser under optical self injection locking

The quality and pulse compression of the 60GHz millimeter wave signals generated by 750μm long InAlGaAs Multi Quantum Well (MQW) passively mode locked laser under free running and optical self injection locked conditions are experimentally characterized in terms of longitudinal modes under certain bias currents that range from 24mA to 90mA. Initially, the MQW laser is characterized in free running condition with no external injection. The measurements reflect that the free spectral range of laser under test is around 61GHz and exhibit more than 22 lasing modes. The laser is then integrated into low phase noise self injection locking oscillator by feeding a part of output RF signal back into the laser cavity to enhance passive mode locking. By doing so the microwave line width of our laser is reduced from 900kHz to 24kHz with significant increase in output of resultant beat tones which exhibits strong passive mode locking. This is the first time that the free running microwave line width of MQW laser is reduced up to this level. It is evident from our experimental investigation that as we increase the power and phase correlation between different longitudinal modes inside laser cavity through optical self injection, the strength of the passively mode locked mechanism is significantly increased and the phase noise of radio frequency signal is drastically reduced.

A revised Hilbert–Huang transformation based on the neural networks and its application in vibration signal analysis of a deployable structure

A revised Hilbert–Huang method is proposed to deal with the non-linear and non-stationary signals generated from any kinds of the sensors, in order to overcome shortcomings of the Hilbert–Huang method, such as the end swings problem and the undesired intrinsic mode functions (IMFs) at the low-frequency range. Firstly, a radial basis function neural network is used as a pre-processor to extend the length of the signal at the both ends. Secondly, the empirical mode decomposition is applied to obtain IMFs. Thirdly, the selection process is employed to select the optimal IMFs. Finally, an energy–frequency–time distribution can be gained after the Hilbert transformation. Two simulated signals are analyzed to explain the pre- and the post-processor, respectively, by using the above two techniques. The efficiencies of the different bases are compared, and the length of signal extended is analyzed. The correlation coefficients between the analyzed signal and the IMFs are introduced to eliminate the undesired IMFs. In this paper, the revised HHT method has been applied to analyze vibration signals of a deployable structure. A simulated solar array setup is built, which contains six parts: the basal body, a locked mechanism, the synchronism mechanism, the connection joints, the driven parts, and two simulated panels. Vibration signals of the solar array setup in the deployed case that is knocked by a single impulse on the middle of the second panel are estimated, and the results show that the revised Hilbert–Huang method is efficient for non-linear and non-stationary signal analysis.

Epitaxial growth of CuScO2 thin films on sapphire a-plane substrates by pulsed laser deposition

An epitaxial film of CuScO2, a transparent oxide semiconductor with a delafossite structure, was grown on an α−Al2O3(112¯0) substrate by a pulsed laser deposition method using a single-phase Cu2Sc2Oδ target. A two-dimensional x-ray reciprocal space mapping measurement revealed that the film was single phase with a rhombohedral crystal structure. The film showed six-fold rotational symmetry in the basal plane, indicating that the film had a twinned domain structure. The epitaxial growth of CuScO2[3R](0001) thin films on α−Al2O3(112¯0) substrates is caused by the uniaxial locked epitaxy mechanism along the ⟨1¯21¯0⟩ direction of the film, and the orientation relationships of the film with respect to the substrate were CuScO2[3R](0001)∕∕α−Al2O3(112¯0) and CuScO2[3R][1¯21¯0]∕∕α−Al2O3[88¯01]. The optical transmittance of the film was larger than 65% in the visible/near-infrared regions, while the energy gap for direct allowed transition was estimated as 3.7 eV. The resistivity of the film, 9.3×106Ωcm at room temperature, significantly decreased to 4.0 Ωcm after both substituting Mg2+ ions for Sc3+ and intercalating excess oxygen. The Mg-doped CuScO2+X(0001) thin film showed optical transmittance of larger than 65% in the visible region, and the Seebeck coefficient was positive, indicating a p-type conductivity.

Dynamic leg volume changes when sitting in a locked and free floating tilt oé ce chair

It is well established that prolonged sitting may lead to swelling of the lower extremities. However, activation of the vein pump system by repeated walking breaks or dynamic tiltable foot-rests have been shown to reduce foot and leg oedema. Some oé ce chairs incorporate tilt mechanisms facilitating movements of the body from the feet up. The present study was undertaken to establish whether a beneficial effect on the transcapillary fluid balance of the legs by enabling such mechanisms could be documented. An oé ce chair where the tilt mechanism could be locked or open was used for the study. The seat position and seat activity level was recorded by a transducer system developed for the study. Calf volume and calf muscle pump activity was detected by mercury strain gauge plethysmography. In the locked position there was a steady increase in volume of mean=1.2% (range=0.8–1.8%) for all participants in the 30-min study period. On the other hand, for all participants there was a decrease in calf volume (mean=0.7%, range=0.1–1.2%, p=0.008) when the tilt mechanism was open (30-min period), irrespective of what study period came first. The study showed that upward seat deflection was not associated with concomitant venous obstruction, since such obstruction was detected in less than 2% of the time period with more than 50% of maximal upward deflection. A locked seat mechanism does not prevent activation of the vein pump mechanism, but the study indicates that oé ce chairs that permit variation in seat angle per se stimulate movements of the leg. This, in turn, activates vein pumps and counteracts local oedema formation in seated working postures.

Structural features associated with movement and ‘catch’ of sea-urchin spines

Spine catch ligaments of a sea urchin Arbacia punctulata were extended under constant load. Ligaments from an undisturbed animal may show any extension rate from zero (catch state) to rapid extension to failure. Replacing the preparation bath with Ca 2+- and Mg 2+-free sea water reversibly abolishes the catch state. The fine structure of the outer muscle layer and inner ligament cone associated with the spine base is described. The unstriated paramyosin muscles bear thin flanges and form compact interlocking rows. Subsurface cisternae are associated with the plasma membrane. The muscles are innervated by glia-free axons ending in bulbous terminals containing lucent synaptic vesicles. The ligament comprises cylindrical bundles of collagen fibrils: one or more minute muscle fibers (paramyosin) lie parallel with and closely adjoining each bundle. The mean diameter of these muscles is 0.3 μg and they occupy 2–3 % of the ligament's cross-sectional area. Axons containing electronopaque secretory droplets accompany the muscles between the collagen bundles: the cell bodies of these neurones generally lie on the outer surface of the ligament. When an urchin points a spine, the ligament on the side of the contracting spine muscle shortens but does not buckle. A function of the intraligamental muscles is to effect this non-buckled shortening. The catch mechanism (which resides entirely within the ligament) may be due either to the intraligamental muscles and/or to a locked polymer mechanism in which matrix molecules between collagen fibrils are reversibly crosslinked by divalent cations.