Effects of wind guide plates on wind velocity acceleration and dune leveling： a case study in Ulan Buh Desert, China

The areas used to be covered by shifting sand dunes have been reclaimed rapidly in recent years. However, it is a challenge to reclaim high sand dunes because it is rather costly to level the high dunes to gentle arable lands. In this study, a wind guide plate was used to change the characteristics of natural wind to level the sand dunes. The use of wind energy could significantly increase the efficiency of dune leveling and decrease the cost. Low wind velocity is a typical characteristic in Ulan Buh Desert of China where the average wind speed is much lower than the threshold velocity for sand movement. The experiment of this study was conducted to accelerate the wind velocity by a wind guide plate to level a sand dune. Results show that the threshold velocity for sand movement is 3.32 m/s at 10 cm above the sand surface in Ulan Buh Desert. A wind guide plate set at an angle less than 50° could significantly increase the wind velocity. The wind velocity could be accelerated up to the threshold velocity for sand movement behind a plate when the plate is at the angles of 20°, 25°, 35° and 40°. The most significant acceleration of wind velocity appears at 1.5 and 3.0 m behind the plate with an angle of 25°. An obvious wind velocity acceleration zone exists behind the wind guide plate when the angles are at 25°, 35°, 40° and 45°, with the most obvious zone under the angle of 45°. The results also show that the total amount of sand transferred over the experimental period increased by 6.1% under the effects of wind guide plates compared to the sand moved without wind guide plates. The results of the study will provide theoretical and practical supports for desert management in sand dune areas.

Orthodontic treatment combined with 3D printing guide plate implant restoration for edentulism and its influence on mastication and phonic function

BACKGROUND Dentition defect,a common clinical oral disease developed in humans,not only causes masticatory dysfunction and articulation difficulties but also affects facial appearance and increases the burden on the intestinal tract.Restorative treatment is the primary option for this disease.However,traditional restorations have many drawbacks,such as mismatch with the body,low reliability,and incomplete occlusal function recovery.AIM to analyze the efficacy of orthodontics combined with 3D printing guide plate implant restoration in treating patients with dentition defects and its influence on masticatory and phonic functions.METHODS A prospective study was carried out in 86 patients with dentition defects who received implant prosthesis after orthodontic treatment in our hospital between January 2018 and January 2019.Those patients were divided into a control group and an intervention group with 43 patients in each group using a random number table.The control group received traditional implant restoration,whereas the intervention group received 3D printing guide plate implant restoration.Treatment outcomes,cosmetic appearance,dental function,implant deviation,and quality of life were compared between the two groups.RESULTS The overall response rate in the intervention group was significantly higher than that in the control group(95.35%vs 81.40%,χ^(2)=4.071,P=0.044).The number of cases with neatly trimmed cosmetic appearance(χ^(2)=4.497,P=0.034),complete coverage(χ^(2)=4.170,P=0.041),and normal occlusion(χ^(2)=5.512,P=0.019)in the intervention group was higher than that in the control group.After treatment,mastication,swallowing,and articulation were significantly improved in both groups.Masticatory(t=2.980,P=0.004),swallowing(t=2.199,P=0.031),and phonic functions(t=3.950,P=0.004)were better in the intervention group than those in the control group.The deviation value and the deviation angle(t=5.440,P=0.000)at the top(t=6.320,P=0.000)and middle parts of the implants(t=22.295,P=0.000)in the intervention group were lower than those in the control group after treatment.Functional limitations,psychosocial and physical pain and discomfort,and total scores decreased in both groups.The functional limitation(t=2.379,P=0.020),psychosocial(t=2.420,P=0.000),physical pain and discomfort(t=6.581,P=0.000),and total scores(t=2.140,P=0.035)were lower in the intervention group than those in the control group.CONCLUSION Orthodontic treatment combined with 3D printing guide plate implant restoration can significantly improve the masticatory and phonic functions,quality of life,and psychological health of patients with dentition defects.Therefore,it is highly recommended in clinic application.

Three-Dimensional Scattering of an Incident Plane Shear Horizontal Guided Wave by a Partly through-Thickness Hole in a Plate

We investigate the three-dimensional （3D） scattering problem of an incident plane shear horizontal wave by a partly through-thickness hole in an isotropic plate, in which the Lamb wave modes are also included due to the mode conversions by the scattering obstacle in the 3D problem. An analytical model is presented such that the wave fields are expanded in all of propagating and evanescent SH modes and Lamb modes, and the scattered far-fields of three fundamental guided wave modes are analyzed numerically for different sizes of the holes and frequencies. The numerical results are verified by comparing with those obtained by using the approximate Poisson/Mindlin plate model for small hole radius and low frequency. It is also found that the scattering patterns are different from those of the SO wave incidence. Our work is useful for quantitative evaluation of the plate-like structure by ultrasonic guided waves.

Establishing a Customized Guide Plate for Osteotomy in Total Knee Arthroplasty Using Lower-extremity X-ray and Knee Computed Tomography Images

Background： The conventional method cannot guarantee the precise osteotomies required for a perfect realignment and a better prognosis after total knee arthroplasty （TKA）.This study investigated a customized guide plate for osteotomy placement in TKAs with the aid of the statistical shape model technique using weight-bearing lower-extremity X-rays and computed tomography （CT） images of the knee.Methods： From October 2014 to June 2015, 42 patients who underwent a TKA in Guizhou Provincial People＆#39;s Hospital were divided into a guide plate group （GPG, 21 cases） and a traditional surgery group （TSG, 21 cases） using a random number table method.In the GPG group, a guide plate was designed and printed using preoperative three-dimensional measurements to plan and digitally simulate the operation.TSG cases were treated with the conventional method.Outcomes were obtained from the postoperative image examination and short-term follow-up.Results： Operative time was 49.0 ＆#177; 10.5 min for GPG, and 62.0 ＆#177; 9.7 min in TSG.The coronal femoral angle, coronal tibial angle, posterior tibial slope, and the angle between the posterior condylar osteotomy surface and the surgical transepicondylar axis were 89.2 ＆#177; 1.7＆#176;, 89.0 ＆#177; 1.1＆#176;, 6.6 ＆#177; 1.4＆#176;, and 0.9 ＆#177; 0.3＆#176; in GPG, and 86.7 ＆#177; 2.9＆#176;, 87.6 ＆#177; 2.1＆#176;, 8.9 ＆#177; 2.8＆#176;, and 1.7 ＆#177; 0.8＆#176; in TSG, respectively.The Hospital for Special Surgery scores 3 months after surgery were 83.7 ＆#177; 18.4 in GPG and 71.5 ＆#177; 15.2 in TSG.Statistically significant differences were found between GPG and TSG in all measurements.Conclusions： A customized guide plate to create an accurate osteotomy in TKAs may be created using lower-extremity X-ray and knee CT images.This allows for shorter operative times and better postoperative alignment than the traditional surgery.Application of the digital guide plate may also result in better short-term outcomes.

3D-Printed Guide Plate Assisted Osteochondral Transplantation for the Treatment of Large Talar Defect:Case Report and Literature Analysis

Osteochondral lesion of the talus(OLT)is a common cause of ankle pain that often occurs in the talar dome and leads to talar cartilage and subchondral bone damage.Osteochondral autograft transplantation is a logical treatment option.It is known that if the cartilage does not heal properly after injury,it degenerates,and osteoarthritis worsens.A three dimensional(3D)-printed guide plate can be used to find the curved articular surface from the donor site which optimally fits the defect in the talus.Herein,we present the case of a 28-year-old man who had an open injury from the crash of a tricycle in the right ankle at the age of 5.Radiographs revealed a large defect in the medial talar dome that affected nearly half of the talar dome.We performed the debridement of the ankle lesion.An osteochondral autograft was harvested from the medial femoral condyle(MFC)with the help of a personalised 3D-printed guide plate.This 3D-printed guide plate simulated the contour of a specific area in the talar dome,which involved the site of the defect.The autograft was then transplanted into the talus defect.The efficacy of this technique was evaluated at 2,4,and 7 months after surgery and proven to be reliable.

Efficiency balance of a light guide plate with microstructures for a see-through head-mounted display

The efficiency balance phenomenon for see-through head-mounted displays with different microstructure con- ditions can be found both theoretically and using optical simulation software. A simple mathematical calculation is used to determine the relationship between the real image （see-through function） energy and the virtual image energy. The simulation is based on factors taken from previous research studies. It is found that the balance value of the optical efficiency remains almost constant （66.63% to 67.38%） under different microstructure conditions. In addition, suitable conditions for the microstructures in see-through head-mounted displays for daily applications can be predicted.

Propagation of guided waves in a bonded plate:Antiplane shear modes

The displacement and stress as well as the dispersion equation for the guided waves of antiplane shear (SH) modes in a bonded plate are presented explicitly. The spring model is used to account for the interface rigidity between the layers of the bonded plate. It is found that the dispersion equation is composed of the terms pertinent with the welded and the cracked or slip boundary conditions with the compliance sT of the spring model as the sum-coefficients. Numerical results for an adhesive plate of aluminum and steel whose wave velocities are very close to each other of equal thickness indicate that the modes of odd order are more sensitive than the even ones to the variations of the bond quality, and so are the higher modes than the lower ones for this special layered plate. The phenomena of the cut-off frequency-shift and the phase velocity decrease resulting from the degradation of the bond quality are found to the modes of odd order, which may be used to evaluate the bond states of the adhesive plate. Numerical results for an adhesive plate of rubber and steel whose wave velocities are very different to each other of equal thickness are presented and discussed as well.