Path Tracking Control of an Autonomous Tractor Using Improved Stanley Controller Optimized with Multiple-Population Genetic Algorithm

To improve the path tracking accuracy of autonomous tractors in operation, an improved Stanley controller (IMP-ST) is proposed in this paper. The controller was applied to a two-wheel tractor dynamics model. The parameters of the IMP-ST were optimized by multiple-population genetic algorithm (MPGA) to obtain better tracking performance. The main purpose of this paper is to implement path tracking control on an autonomous tractor. Thus, it is significant to study this field because of smart agricultural development. According to the turning strategy of tractors in field operations, five working routes for tractors were designed, including straight, U, Ω, acute-angle and obtuse-angle routes. Simulation tests were conducted to verify the effectiveness of the proposed IMP-ST in tractor path tracking for all routes. The lateral root-mean-square (RMS) error of the IMP-ST was reduced by up to 36.84% and 48.61% compared to the extended Stanley controller and the original Stanley controller, respectively. The simulation results indicate that the IMP-ST performed well in guiding the tractor to follow all planned working routes. In particular, for the U and Ω routes, the two most common turning methods in tractor field operations, the path tracking performance of the IMP-ST was improved by 41.72% and 48.61% compared to the ST, respectively. Comparing and analyzing the e-Ψ and β-γ phase plane of the three controllers, the results indicate that the IMP-ST has the best control stability.

A new species of Corallana Dana, 1852 (Crustacea: Isopoda: Corallanidae) from the Andaman Islands, northern Indian Ocean

Corallana mishrai sp. nov. collected from dead mangrove roots at Kodiyaghat, South Andaman, Andaman Islands, India is described and illustrated in detail. Corallana mishrai sp. nov. the first definitive record of the genus from India, is characterized by: frontal lamina with short straight (or very weakly convex) lateral margins and the anterior margin forming a strong acute median point; pleotelson length 0.76 greatest width, posterior margin with 5 robust setae; uropodal exopod 7 times longer than greatest width, extending beyond endopod by one fourth of its length; endopod lateral margin slightly convex with 4 RS and PMS, apex forms a slightly obtuse angle with long simple setae, mesial margin weakly convex with 2 RS and PMS; mandible bidentate; transverse row of 6 tubercles present on pereonite 1 and pleonites 2, 3 and 4 lacking lateral tubercles. The status of the genus and its species are reviewed, and two species are transferred to new combinations: Argathona kulai (Bruce, 1982) comb. nov. and Tachaea bidentata (Jones et al. 1983) comb. nov.

Influence of the position of recessed outdoor units and louvre blade angle on the performance of split air conditioners

In residential air conditioning systems, outdoor units are often installed in the recesses of building facades and shaded by louvres; however, different unit installation positions and louvre blade angles affect the thermal environment around the outdoor unit and the energy efficiency ratio (EER) of the air conditioner. In this study, the effects of the outdoor unit installation position and louvre blade angle on the EER when a single outdoor unit was installed in a recess were investigated by experiments on a 1.5 hp air conditioner (rated power of the air conditioner is 3.5 kW), and the influence of the spacing and angle between two outdoor units on the air conditioner EER when two outdoor units were installed in the same recess was explored. The results of the research indicate that when a single outdoor unit is installed in the recess, the EER increases with an increase in the distance between the inlet of the outdoor unit and the wall. To meet the three-level standard of air conditioner EERs, the distance between the inlet and wall needs to be greater than 300 mm. The EER first increased and then decreased slowly with the increase in the distance between the outdoor unit outlet and louvre; thus, the distance between the outlet and louvre should not be less than 300 mm. The EER first increased and then decreased with the increase in the blade angle, and thus, the blade angle should not be greater than 20°. When two outdoor units are installed in the same recess, each installation mode, “horizontal installation” (same height and collinear), “perpendicular installation” (same height and perpendicular), “angle installation” (same height and obtuse angle), and “up and down parallel installation” (different heights and parallel), has an optimum installation distance and angle.

The termite genus Glyptotermes (Isoptera: Kalotermitidae) in Miocene amber from Ethiopia

A new species of drywood termite (Isoptera: Kalotermitidae) is described from a nearly complete alate specimen preserved in early Miocene Ethiopian amber. Glyptotermes abyssinicus new species is distinguished by its U-shaped head with 12-segmented antennae, the ocelli separated from the eye margin, the right mandible with an obtuse angle between the apical and first marginal teeth, the left mandible with an obtuse angle between the apical and first + second marginal teeth, and the wing venation. This is the first termite reported from Ethiopian amber, and the fourth Miocene species of the extant genus Glyptotermes Froggatt, 1897, together with species previously described from diatomites of China and amber from the Dominican Republic. As the oldest report of the genus known from Africa, G. abyssinicus n. sp. constitutes an interesting new record for the biogeographical history of the kalotermitid lineage. UUID: http://zoobank.org/7670b045-fb31-4809-8116-4d14c4dd275b

Barkeria uruapani (Laeliinae, Epidendroideae, Orchidaceae), a new species from western Mexico

Barkeria uruapani, a new orchid species endemic to Michoacán, Mexico, is described and illustrated. Information on its distribution, habitat and conservation status is provided. The new species is also compared with B. barkeriola and B. uniflora, and an updated key to all Barkeria species is included. Diagnostic features of B. uruapani include the branching inflorescences with simultaneous anthesis, the elliptical-obovate lip with a large magenta spot, the revolute wings of the column and the lateral sepals forming an obtuse angle.

Grounding of Design and Technology Parameters of Combined Coulter Furrow Opener of Precision Seed Drill

A formation of a seedbed is an important step during seed sowing process. A quality of seedbed formation influences on seeds distribution along both a row and a depth and is triggering the opportunity to obtain early and even sprouts. The design of the furrow opener is the main element that has a direct impact on the qualitative formation of seedbed and technological parameters of coulter operation. During the research, there has been analyzed the modern construction of precision seed drills coulters and specified advantages and disadvantages of their operation. It has been established that the most advanced are coulters having a working section with a combined angle (sharp and obtuse) of entry into the soil. The attained results afforded to develop an improved design of the coulter furrow opener of the precision seed drill. There was brought forward a combined wedge furrow opener, the upper part of which has a working section with a sharp angle of entry into the soil, lower - and compactor, located in the rear part of the furrow opener, which forms seedbed has a working surface with an obtuse angle of entry into the soil. There were obtained analytical dependences targeted to determine the main structural and technological parameters of the operating elements of a combined coulter furrow opener which is used to seed cultivated crops: the angles of entry into the soil of the upper and lower part of the furrow opener, compactor in the rolling plane and the angle of tip of the furrow opener in the horizontal plane.

Swords and Daggers Without a Metal Pommel from the Meotian Sites of the Right Bank of the Kuban

The article is devoted to typology and chronology of swords and daggers without a metal pommel from the Maeotian cemeteries of the right bank of the Kuban. We took into account 57 pieces of this type of weapon from closed complexes. In this paper, we use the typological scheme of A.M. Khazanov, developed on the materials of the Sarmatian armament. The Maeotian swords and daggers of mentioned group are divided into three types: 1 – swords and daggers with a rain-guard; 2 – swords and daggers without a rain-guard, the blade and the hilt make an obtuse angle; 3 – swords and daggers without rain-guards, the blade and the hilt make a right angle. Metal tangs of hilts differ by shape and size; thus they are divided into two variants: “a” – rectangular or triangular; “b” – a long pin. The swords of the “a” variant had wooden overlays on the handles, sometimes fastened with rivets or winding, and the handles of the “b” variant swords were mounted on a tang. Chronological dating of the burials indicates that bladed weapon of this type appears among the Maeotians of the Kuban right bank in the beginning of the 1st cent. AD and remains there until the middle of the 3rd cent. AD. And the main time of its use is the 1–2 cent. A.D. Swords and daggers of all types from Maeotian assemblages have existed at the same time, just like ones from the Sarmatian burials of the Lower Volga region. But, unlike the Sarmatian sites with no predominance of any particular sword type, the Maeotians show clear advantage of type 2 blades.

Probing the Fault Complexity of the 2017 Ms 7.0 Jiuzhaigou Earthquake Based on the InSAR Data

On 8 August 2017, a surface wave magnitude (Ms) 7.0 earthquake occurred at the buried faults extending to the north of the Huya fault. Based on the coseismic deformation field obtained from interferometric synthetic aperture radar (InSAR) data and a series of finite fault model tests, we propose a brand-new two-fault model composed of a main fault and a secondary fault as the optimal model for the Jiuzhaigou earthquake, in which the secondary fault is at a wide obtuse angle to the northern end of the main fault plane. Results show that the dislocation distribution is dominated by sinistral slip, with a significant shallow slip deficit. The main fault consists of two asperities bounded by an aftershock gap, which may represent a barrier. In addition, most aftershocks are located in stress shadows and appear a complementary pattern with the coseismic high-slip regions. We propose that the aftershocks are attributable to the background tectonic stress, which may be related to the velocity-strengthening zones.

A Novel Algorithm for Path Planning of the Mobile Robot in Obstacle Environment

—In this paper, a design method of smoothing the path generated by a novel algorithm is proposed, which makes the mobile robot can more rapidly and smoothly follow the path and reach the target point. No matter the attitude vector angle is an acute angle or obtuse angle, there is no doubt that we can find the right curve, including polar polynomial curves and piecewise polynomial functions, which makes the path length and the circular arc tend to be similar and guarantees the shorter path length. In the condition of meeting the dynamic characteristics of the mobile robot, the tracking speed and quality are improved. Therefore, the symmetric polynomial curve and the piecewise polynomial function curve are used to generate a smooth path. This novel algorithm improves the path tracking accuracy and the flexibility of the mobile robot. At the same time, it expands the application range of mobile robot in structured environment.

Imaging findings of cutaneous angiosarcoma of the scalp: Comparison with cutaneous squamous cell carcinoma

Purpose This study aimed to evaluate imaging findings of cutaneous angiosarcoma (cAS) of the scalp compared with those of cutaneous squamous cell carcinoma (cSCC). Methods This study included 15 patients with primary cAS and 10 with primary cSCC of the scalp. Seven patients with cAS and eight with cSCC underwent magnetic resonance imaging, and 11 patients with cAS and eight with cSCC underwent 18F-fluorodeoxyglucose–positron emission tomography/computed tomography imaging. Imaging findings for both pathologies were retrospectively reviewed and compared. Results All 15 cAS cases were elevated lesions with an obtuse angle, invading the subcutaneous fat tissue. Multiple lesions were observed in only five cAS cases (33%) and no cSCC cases. Maximum diameter-to-height ratio was significantly higher in cAS than in cSCC (3.3 ± 1.0 versus 2.3 ± 0.6; p < 0.01). On T2-weighted images, intratumoral hypointensity (86% versus 13%; p < 0.01) and mixed hyper- and hypointensity (71% versus 0%; p < 0.01) were observed more frequently in cAS than in cSCC. No significant differences were observed between cAS and cSCC regarding flow void (29% versus 25%; p = 0.656). Maximum standardized uptake values were marginally significantly lower in cAS than in cSCC (5.6 ± 3.1 versus 10.5 ± 6.6; p = 0.078). Conclusions Cases of cAS of the scalp always exhibited flat elevated lesions with invasion of the subcutaneous fat tissue. Compared with cSCC, intratumoral hypointensity and mixed hyper- and hypointensity on T2-weighted images were more frequent in cAS. These findings will help with the differential diagnosis of cAS.