Concave Type Research Articles

Influence of trehalose additives on the properties of poly(vinyl alcohol) cryogels formed in aqueous as well as in organic media

Physical (non-covalent) macroporous cryogels of poly(vinyl alcohol) (PVACGs) are formed as a result of the consecutive freezing of concentrated PVA solutions, their incubation in a frozen state and then thawing. In this study the influence of the additives of trehalose and the solvent used on the PVA cryotropic gel-formation, as well as on the properties of the respective PVACGs was explored. It was shown that both the rigidity and the heat endurance of cryogels formed in the DMSO medium in the presence of trehalose progressively increased with increasing the additive concentration. It turns, in the case of cryogels prepared in the aqueous medium in the presence of trehalose the dependences of the physicomechanical characteristics on the additive concentration were of a bell-like (concave) type, while the heat endurance of the samples grew monotonically.

Effect of swirl at intake manifold on engine performance using ethanol fuel blend

ABSTRACTEthanol fuel is widely used as an alternative fuel in spark ignition engines. The use of ethanol reduces dependence on fuel from the fraction of hydrocarbons. As such, adding swirl generators to the intake manifold aims to make the internal airflow more turbulent. The influence of swirl on the performance, emissions, and combustion in a constant speed Spark Ignition (SI) engine was studied experimentally. Also, the effects of the addition of ethanol in the fuel on engine performance and emissions under development of the intake manifold with a swirl generator were determined. Thus, the study analyses the effects of adding a swirl generator to the intake manifold on engine performance, fuel consumption, and emissions produced. Influence of the swirl generator on the airflow and swirl pattern testing is done on the three types of swirl generators, which are the concave, flat bottom, and symmetrical with different angle positions. Engine experiment was performed at 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, and 5,000 rpm engine speed at WOT using a concave swirl type generator. Response Surface method (RSM) was used to find the optimum intake manifold design according to response (flow and swirl) and independent variables (a type of swirl generators and angle positions). The concave swirl type generator at 6.53 angle position is considered to be optimum for this particular engine. The highest engine torque and BSFC were with a swirl generator intake manifold. The HC and CO emissions increased with intake manifold with a swirl generator. The CO2 emission reduced with swirl generator intake manifold by 2%, 3%, and 5% with gasoline E10 and E20 compared to the standard intake manifold.

Ginsenoside Rd improves behavioral impairment of rats with acute plateau status by modulating synaptic plasticity

ObjectiveTo investigate the protective effect of ginsenoside Rd on the improvement of the behavior and synaptic plasticity in rats with acute plateau status. MethodsA total of 60 Wistar rats were randomly divided into the control group, the model group, and the intervention group, with 20 rats in each group. The model was established in low-pressure oxygen chamber simulating the plateau, and the intervention group was administered with ginsenoside. Electron microscope was used to observe synaptic ultrastructure of hippocampal CA1 area, and analyze the structural parameters on the Gray I synaptic interface. Morris water maze and Y electric maze experiment were used for behavioral detection. ResultsCompared with the control group, the number of electrical stimulation required for rat to avoid was increased in the model group, the latency in the Morris water maze was prolonged, the swimming distance was increased, and the frequency of crossing the platform was decreased. Under the electron microscope, the synaptic cleft was increased, the length of the synaptic active area was shorter, the postsynaptic density (PSD) was thinner, the flat synapse was increased, and the concave and perforated types were significantly reduced. Compared with the model group, the number of electrical stimulation required for rat to avoid was decreased in the intervention group, the latency in the Morris water maze was shortened, the swimming distance was decreased, and the frequency of crossing the platform was increased. Under the electron microscope, the synaptic cleft was decreased, PSD was thicker, the flat synapse was decreased, and the concave and perforated types were increased. ConclusionLow pressure and low oxygen environment of plateau damages the plasticity changes of the synaptic structure and function. And to a certain extent, ginsenoside Rd reverses Gray I synaptic interface structure parameters, so as to improve the behavior performance of model rats at high altitude condition.

A quasi-linear utility function of fractional agent-based computational economic systems defined by Palm calculus

A new quasi-linear utility function is introduced by using the fractional calculus together with Palm calculus for agent computational economic systems. We aim to study the boundedness of the function in some Banach spaces. Moreover, we solve a control problem by maximizing the utility function under some conditions for two cases: concave and non-concave types. The application shows that the new approach is more efficiency and capacity than the regular one.

Symplectic divisorial capping in dimension $4$

We investigate the notion of symplectic divisorial compactification for symplectic 4-manifolds with either convex or concave type boundary. This is motivated by the notion of compactifying divisors for open algebraic surfaces. We give a sufficient and necessary criterion, which is simple and also works in higher dimensions, to determine whether an arbitrarily small concave/convex neighborhood exist for an $\omega$-orthogonal symplectic divisor (a symplectic plumbing). If deformation of symplectic form is allowed, we show that a symplectic divisor has either a concave or convex neighborhood whenever the symplectic form is exact on the boundary of its plumbing. As an application, we classify symplectic compactifying divisors having finite boundary fundamental group. We also obtain a finiteness result of fillings when the boundary can be capped by a symplectic divisor with finite boundary fundamental group.

Effects of menopausal factor on fine anatomy of bladder urethra and vagina in women undergoing vaginal delivery

Objective: To explore the effects of menopausal factor on fine anatomy of bladder, urethra and vagina in women undergoing vaginal delivery. Methods: Gynecological patients in Nanfang hospital from January 2013 to October 2016 were collected, and then the patients whose MRI images quality meet the require of reconstruction, with the history of vaginal delivery experience, without any cesarean section experience, and the first labor time was ≤30 years old were enrolled. The patients who had pelvic floor dysfunction when done MRI examinations were excluded. Finally, 238 cases were randomly selected out, and 238 models of data were reconstructed and measured by Mimics and UG software. The independent t test was used to do the comparison between menopausal group and those not yet menopause. Results: First, we built 238 3D models totally. Second, the parameters related with bladder and urethra: the angle of bladder and urethra, β angle, urethra pubic angle, α angle, retropubic space, the length between bladder neck and edge of pubic midpoint, and urethral striated muscle thickness of menopausal group were bigger than those of pre-menopausal group. While for the urethra tilt angle, the former group was smaller than that of the latter group. But there was no significant statistical differences between two groups. Third, the parameters related with vagina: the proximal urethral vaginal gap of the post-menopause group was smaller than that of pre-menopausal group, while for the middle and distal urethral vaginal gap, the former group was bigger than that of the latter group. The length and width of vaginal anterior wall of the post-menopausal group were smaller than those of pre-menopausal group. Beside the middle urethral vaginal gap, all the difference between two groups had no statistical meaning. The 2D shape of axial vaginal, H type occupation of the former group was obviously lower than that of the latter group. Conclusions: Menopause has an effect on fine anatomy of pelvic organ. Especially on the shape of vagina, the middle urethral vaginal gap become much wider after menopause, the occupation of shallow concave type become much higher post-menopausal. It means the lateral and backward support function of the urethra and vagina is relatively weakened after menopausal, and the shape of vagina become smaller.

Energy-minimum optimization of the intelligent excavating process for large cable shovel through trajectory planning

Large cable shovel (LCS) is a complex engineering machine which is widely used in the open pit mine. It is characterized by low efficiency, high maintenance cost, and high energy consumption if manipulated by an inexperienced operator. To address these challenges, intelligentization could be a feasible solution. In this work, an intelligent excavation system is put forward and the corresponding energy-minimum optimization through trajectory planning of the optimal excavation is developed to realize the intelligentization of the LCS. Firstly, the excavating resistance acting on the dipper is modeled and the corresponding forces are analyzed. Then, by establishing the kinetics and dynamic models of the excavating process, the point to point (PTP) trajectory planning method is developed by setting the objective to minimize the energy consumption per unite volume material. Polynomial curves in different degrees are used in the PTP planning method and the optimal one is compared with the conventional S-curve in terms of the excavating performance. To explore the advantage of the proposed intelligent system and the corresponding trajectory planning based energy-minimum optimization method, four types of ore piles with different pile angles are compared with respect to the excavating performance. Results show that the larger the pile angle is, the later the maximum hoist power and crowd power will appear. Further, the effects on the excavating performance from different ore piles with complex terrains, including the flat type, concave type, convex type, and concave-convex type, are also studied in the numerical experiments. It is found that the trajectory based energy-minimum optimization method for the intelligent LCS can significantly save excavation energy as well as keep sufficient fill factor.

Cryostructuring of polymeric systems. 48. Influence of organic chaotropes and kosmotropes on the cryotropic gel-formation of aqueous poly(vinyl alcohol) solutions

Physical (non-covalent) macroporous cryogels of poly(vinyl alcohol) (PVACGs) are formed as a result of the consecutive freezing of concentrated PVA solutions, their incubation in a frozen state and then thawing. If some additional low-molecular-weight solutes are present in the feed system to be gelled cryogenically, such additives can affect more or less the physicochemical properties and the microstructure (porous morphology) of the resultant PVACGs. In this study the influence of the additives of organic non-ionic and ionic chaotropes (urea and guanidine hydrochloride) or kosmotropes (trehalose and hydroxyproline) on the PVA cryotropic gel-formation, as well as on the properties and structural features of the respective PVACGs was explored. It was shown that both the strength and the heat endurance of cryogels formed in the presence of chaotropes progressively decreased with increasing the additive concentration. In turn, in the case of cryogels prepared in the presence of kosmotropes the dependences of the physicomechanical characteristics on the additive concentration were of a bell-like (concave) type, while the heat endurance of the samples grew monotonically. The microstructure of the PVAGCs containing various amounts of the chaotropes and the kosmotropes was studied using the optical microscopy of thin sections followed by the mathematical analysis of the images. The average size of the pore cross-section and the “conditional porosity” of the respective specimens were characterized quantitatively.

The lower limit of the flowing pore throat radius in the extra-low permeability reservoir

In this paper, a method for determining the lower limit of flowing pore throat radius of the extra low permeability reservoir in the periphery of Changyuan Oil Fields is given. The capillary pressure curve is divided into linear type and concave type. The nuclear magnetic resonance (NMR) T2 spectrum is divided into 3 types: the left peak is greater than the right peak, the left peak is equal to the right one, and the left peak is smaller than the right one. The method for determining the lower limit of flowing pore throat radius is, first, converting the nuclear magnetic resonance T2 spectrum to the capillary pressure curve calculated, then fitting the capillary pressure curves measured by the constant speed mercury injection experiment and the capillary pressure curve calculated. After finding the relevant parameters, converting the horizontal axis of the NMR T2 spectra from relaxation time to pore throat radius, and the pore throat radius corresponding to the T2 cutoff value is the lower limit of the flowing pore throat radius. The lower limit of the flowing pore throat radius of the extra low permeability Fuyang Oil Reservoir in the periphery of Changyuan Oil Fields is about 0.68μm

Research on Static Contact Behavior and Simulation for Rail Grinding by Abrasive Belt Based on Concave Type Contact Wheel

Research on Static Contact Behavior and Simulation for Rail Grinding by Abrasive Belt Based on Concave Type Contact Wheel

A study of the micro-hole geometry evolution on glass by abrasive air-jet micromachining

Abrasive air-jet (AAJ) micromachining has become an attractive technology for the fabrication of micro-structures on a wide range of engineering materials. However, problems specific to effective mould construction still remain challenging. This paper presents a study on the evolution of micro and blind holes on glass during abrasive air-jet machining. Experiments were conducted under different practical settings of air pressure, particle mass flow rate and drilling time. A 3D laser measurement microscope was used to characterize the machined hole profiles. It was found that there was a clear evolution of the profiles of the hole bottom surfaces. Three types of hole surface contours, i.e., convex, flat, and concave (reverse bell-shaped), were obtained within the operating range used, in which the first two types have rarely been reported in literature. The profile variation took place along with the setting parameters of particle flow rate and air pressure, which indicated that the particles distribution density across the cross section of a cylindrical nozzle also varied with the setting parameters. At a low flow rate, the hole bottom was formed with a convex shape, which might be attributed to the fact that the distribution of particles at the nozzle centre was less than that around the brim. As the particle flow rate increased, the bottom surface evolved from convex to flat or even concave. With a proper setting, AAJ can therefore be used to fabricate a micro hole with a desired bottom surface profile. The variation of abrasive particle distribution in the jet in the AAJ micromachining might be attributed to the flow bounce back and stagnation effects when the jet impacts on a target workpiece.

직접모사법을 이용한 형상 변화에 따른 미소채널 유동 해석

In the present study, to investigate the characteristics of subsonic rarefied gas flows in micro-channels with shape change, flow simulations of micro-channels with different geometries were conducted using a direct simulation Monte-Carlo (DSMC) solver based on unstructured meshes. For simulating micro-channel flows like pressure driven flows, the pressure boundary conditions at the inlet and the exit were additionally applied. Verification of the boundary condition was conducted by comparing with other researchers’ DSMC simulations with the pressure boundary condition. After verification of the boundary condition, the straight micro-channel of 15μm × 1μm was considered for the baseline channel. The pressure conditions at the inlet and the exit were 5×105 Pa and 1.66×105 Pa, respectively. The inlet gas temperature and wall temperature were both 300K, and a fully diffuse reflecting wall was considered. Three types of change of shapes were considered. The change of the length, height and bend angles were treated for this study. Firstly, to investigate the effects of the change of length, half and twice of the baseline channel length were considered. It was shown that the pressure gradient was dominantly affected by the change of the lengths. As a result, the velocity was more accelerated for short length channel than for the baseline channel. On the other hand, when the heights were become higher, the changes of flow properties were greater than the baseline channel due to the area of boundary layers or the forces by the pressure gradient. Finally, the effects of the bend angles in micro-channels were investigated with several bend angles. The angles were considered from 0 to 135 degrees. When the angle became greater, the flow separation was generated at the concave type corner. For larger angles, the variation of flow properties at the corner became greater. Flow properties at the exit were different trend from those at the corner. Pressure and density at the exit were not dependent on the bend angles, whereas the velocity at the exit was increased according to the bend angles.

Beam aperture modifier design with acoustic metasurfaces

In this paper, we present a design concept of acoustic beam aperture modifier using two metasurface-based planar lenses. By appropriately designing the phase gradient profile along the metasurface, we obtain a class of acoustic convex lenses and concave lenses, which can focus the incoming plane waves and collimate the converging waves, respectively. On the basis of the high converging and diverging capability of these lenses, two kinds of lens combination scheme, including the convex–concave type and convex–convex type, are proposed to tune up the incoming beam aperture as needed. To be specific, the aperture of the acoustic beam can be shrunk or expanded through adjusting the phase gradient of the pair of lenses and the spacing between them. These lenses and the corresponding aperture modifiers are constructed by the stacking ultrathin labyrinthine structures, which are obtained by the geometry optimization procedure and exhibit high transmission coefficient and a full range of phase shift. The simulation results demonstrate the effectiveness of our proposed beam aperture modifiers. Due to the flexibility in aperture controlling and the simplicity in fabrication, the proposed modifiers have promising potential in applications, such as acoustic imaging, nondestructive evaluation, and communication.

Study of lesions of the lumbar endplate based on the stage of maturation of the lumbar vertebral body: the relationship between skeletal maturity and chronological age.

The lesion of the lumbar endplate is sometimes identified in the vertebrae of children and adolescents. The purpose of this study is to compare between skeletal maturity and chronological age. The second purpose of this study is to clarify the lesions of the lumbar endplate based on the maturation of the lumbar vertebral body. Six hundred and thirty-two (485 men and 147 women) consecutive patients were included. The mean age at the first medical examination was 13.8years. Their skeletal maturity was evaluated based on the appearances of the secondary ossification center of L3. The area of the endplate lesions was classified into five types. The apophyseal stage was observed from 10years old to 18years old, and the apophyseal stage was shown the peak at 14years old. The appearance of the apophyseal ring was observed earlier in female patients than in male patients. For the concave type, the lesion at upper level vertebra was more prevalent. The anterior and middle type of the lesion at upper level vertebra was more prevalent. For the posterior type, the lesion of the inferior rim of L4 and the lesion of the rim of L5 were more prevalent. This study emerged after comparing skeletal maturity based on the maturation of the lumbar vertebral body with the chronological age of a large number of patients and examining the lesions of the lumbar endplate based on the stage of maturation of the lumbar vertebral body.

Twin Rectangular Fork-Like Capacitance Sensor to Flow Regime Identification in Horizontal Co-Current Gas–Liquid Two-Phase Flow

In this paper, a twin rectangular fork-like capacitance (TRFLC) sensor to recognize the flow regime of gas-oil two-phase flow in a horizontal pipe is proposed. Two phase flow experiment is carried out in a 26.6-mm ID horizontal pipe to determine the response of TRFLC sensor on different flow regimes. Both measuring and exciting electrodes consist of a base and double rectangle blades, which are placed alternately. The finite-element method (FEM) is used to calculate the sensitivity field of the sensor. The effect of sensor geometry on the distribution of sensitivity field and the optimal sensor structure is presented. Based on FEM and experimental results, the sensitivity of TRFLC was higher than the previous concave electrode (overall sensitivity of TRFLC 3.27 pF and concave 2.19 pF). Simulation results show that two blades for each electrode have more sensitivity than three or four blades in the regions near to the center of the pipeline and more uniform sensitivity in whole section of the pipe. The flow variations especially in the center of the pipeline were traced with higher sensitivity than concave type. As a result, the flow regimes such as slug can be identified with more accuracy. The flow regimes were classified using wavelet transforms and power spectral density (PSD). The wavelet variance is not sufficient to flow regime assignment due to some flow regimes overlapping. The wavelet variance in conjunction with the cumulative PSD solves this problem and presents a very useful tool to flow regime classification.

A preliminary study on the location of the stabilizing piles for colluvial landslides with interbedding hard and soft bedrocks

The paper presents a study on the location determination of stabilizing piles in colluvial landslides with the interbedding of hard and soft bedrocks. A double-arc model is proposed to describe the shape of sliding surface of colluvial landslides, and the corresponding slope surface can be divided into three types, namely the concave type, straight line type, and convex type, respectively. The driving force of colluvial landslides and interbedding characteristics of hard and soft bedrocks are two important factors affecting the determination of optimal location for stabilizing piles. The results indicate that the stabilizing effect of the piles mainly depends upon the hard bedrock. The effect of the location of hard layer bedrock on the pile deformation is represented by the location coefficient. It is found that the optimal location of stabilizing pile locates where both top and bottom hard layers are present; and, the location with a top soft layer is unfavorable, particularly when the hard layer has a large location coefficient. The case study of Yanguan landslide illustrates that the location of stabilizing pile is determined with the proposed method is effective, with a considerable decrease in both the displacement and internal force of the stabilizing piles.

Digitalized analysis of philtral anatomy for planning individual treatment

Restoration of the philtral region following traumatic, cleft, and tumor surgeries is often difficult due to influence of this feature to whole facial beauty. The aim of this study is to investigate the types and measurements of the philtrum and its relationship with the upper lip using a software. Standard personal photographs of the philtral region were obtained from 200 young adults participated in this study. Linear analyses (the lengths of philtral column and dimple; the philtral width) and angular analyses (apex and central angles of Cupid's bow) were measured as reference points. As for the shape of the philtral column, it was categorized as four distinct types: parallel, triangular, concave, and unclear type. The philtral width was 11.37 ± 1.9mm in males, 10.21 ± 1.80mm in females. The length of the philtral dimple was 18.16 ± 3.6mm in males, 18.16 ± 3.6mm in females. Compared with women, both of the measured average philtral reference lengths displayed a significantly greater value in men. In the meanwhile, compared to women, the angular measurements of Cupid's bow (i.e., the apex and central angle of Cupid's bow) were smaller in men. It was 127.47 ± 12.74°mm in males, 134.1 ± 11.38°mm in females. The triangular and concave types were associated with a substantial fraction in men, whereas the triangular and parallel types were predominant in women. There were significant gender differences in the esthetic rankings of philtral column shapes. These results suggest digitalized reference values relative to the philtral column which may increase the success of the individual reconstructive treatment of the surgical procedures and reduce possible asymmetrical appearance. With the help of certain software, this research has made possible to investigate the ideal parameters of philtral construction in defining the best surgical solution for the patient.

Comparative study of the morphology of the female seminal receptacles of Ilia nucleus and Persephona mediterranea (Decapoda, Brachyura, Leucosiidae)

Because of the poor knowledge of the morphology of the female reproductive organs of most brachyuran crabs, this study investigated two Atlantic representatives of the family Leucosiidae, Ilia nucleus (Linnaeus, 1758) and Persephona mediterranea (Herbst, 1794), using histological methods and magnetic resonance imaging (MRI). While the vagina conforms to the concave type, the arrangement of the two chambers of the seminal receptacle differs strongly from that of other eubrachyuran sperm storage organs. Both chambers are oriented laterally within the crab's body. This is in contrast to the dorso-ventral orientation described in most other known brachyuran crabs. The lateral chamber is covered by cuticle, whereas the medial chamber is covered by a holocrine glandular epithelium. The oviduct connection is located ventrally, posterior to the vagina. The oviduct orifice is characterized by a transition from the epithelium lining the oviduct to the seminal receptacle's holocrine glandular epithelium. Moreover, muscle fibres are attached to the oviduct orifice and to the sternal cuticle. This musculature can be interpreted as an important feature in the fertilization and egg-laying process by supporting and controlling the inflow of eggs into the seminal receptacle lumen. The results of this study are compared to the morphology of the seminal receptacle of another leucosiid crab, Ebalia tumefacta (Montagu, 1808), and to those of other known eubrachyuran crabs.

Predictions of the quantum landscape multiverse

The 2015 Planck data release has placed tight constraints on the class of inflationary models allowed. The current best fit region favors concave downwards inflationary potentials, since they produce a suppressed tensor to scalar index ratio r. Concave downward potentials have a negative curvature , therefore a tachyonic mass square that drives fluctuations. Furthermore, their use can become problematic if the field rolls in a part of the potential away from the extrema, since the semiclassical approximation of quantum cosmology, used for deriving the most probable wavefunction of the universe from the landscape and for addressing the quantum to classical transition, breaks down away from the steepest descent region. We here propose a way of dealing with such potentials by inverting the metric signature and solving for the wavefunction of the universe in the Euclidean sector. This method allows us to extend our theory of the origin of the universe from a quantum multiverse, to a more general class of concave inflationary potentials where a straightforward application of the semiclassical approximation fails. The work here completes the derivation of modifications to the Newtonian potential and to the inflationary potential, which originate from the quantum entanglement of our universe with all others in the quantum landscape multiverse, leading to predictions of observational signatures for both types of inflationary models, concave and convex potentials.

Anatomical variations of the trochlear notch angle: MRI analysis of 78 elbows.

Little is known about the anatomical variations of the trochlear notch angle, nor do we know whether the cartilaginous layer modifies the trochlear bony contour. Our aim was to assess the variability of the bony and cartilaginous trochlear notch angles. We assessed 78 healthy elbows (39 patients, 19 females and 20 males) with a mean age of 28years (range 21-32). High-definition MRI coronal scans at the level of the flexion-extension axis were performed. The cartilage thickness, the notch angle, and trochlear width were calculated at the level of the deepest point of the trochlear sulcus, the edge of the lateral and medial ridge. Patient height was used as indirect measurement of humerus length. Pearson correlation and Student's t tests were performed. Mean cartilage thickness was 1.00mm (range 0.62-1.83), with significant differences between the medial trochlear ridge and the other landmarks. The notch angle ranged from 124° to 156° (mean 142°) with no differences between the bony and cartilage layers. Trochlear width ranged from 1.57 to 2.75cm (mean 2.24) and correlated with humerus length. No correlation emerged between the trochlear notch angle, trochlear width, or humerus length. The only significant difference between sexes was the width value, with a wider trochlea in males. The trochlear notch angle varies considerably, determining anatomical variations in trochlear shape which ranges from less concave to more concave types. Moreover, the cartilaginous layer does not modify this angle at the level examined. These findings may be relevant to anatomical implant design for distal humerus hemiarthroplasty.