Yield, Nutrient Composition, and Horse Condition in Integrated Crabgrass and Cool-Season Grass Rotational Grazing Pasture Systems

Integration of warm-season grasses into traditional cool-season pastures can increase summer forage for grazing cattle. The aim of this study was to determine impacts of this practice on yield and nutrient composition of equine rotational pasture systems as well as horse body condition. Two 1.5 ha rotational systems (6-0.25 ha sections/system) were evaluated: a control system (CON) [all sections mixed cool-season grass (CSG-CON)] and an integrated system (IRS) [3 CSG sections (CSG-IRS) and 3 Quick-N-Big crabgrass [Digitaria sanguinalis (L.) Scop.] (CRB-IRS)]. Three horses per system grazed in 3 periods: EARLY (mid-May to mid-Jul), SLUMP (mid-Jul to mid-Sep), and LATE (mid-Sep to mid-Nov). Herbage mass (HM) was measured prior to each rotation and samples were collected (0800-1000 h) for nutrient analysis. Grazing days were tracked to calculate carrying capacity (CC). Horse condition measures were assessed monthly. Over the full grazing season, 9125 kg of forage was available for grazing in IRS vs. 6335 kg in CON. The CC was 390 horse d for IRS, while only 276 horse d for CON. Total HM/section did not differ during EARLY when CRB was not available (CSG-IRS: 2537 ± 605; CSG-CON: 3783 ± 856 kg/ha), but CC was greater in CSG-IRS (220 ± 37 horse d/ha) than CSG-CON (92 ± 26 horse d/ha; P = 0.03). In SLUMP, both HM and CC were greater in CRB-IRS (HM: 4758 ± 698 kg/ha; CC: 196 ± 31 horse d/ha) than CSG-IRS (HM: 1086 ± 698 kg/ha; CC: 32 ± 31 horse d/ha) or CON (HM: 970 ± 493 kg/ha; CC: 46 ± 22 horse d/ha; P < 0.02). While HM did not differ by section type in LATE (1284 ± 158 kg/ha), CC was greater in CSG-CON (84 ± 9 horse d/ha) vs CRB-IRS (32 ± 13 horse d/ha; P = 0.03) and CSG-IRS (40 ± 13 horse d/ha; P = 0.06). During SLUMP, water-soluble carbohydrates (WSC) were lower in CRB-IRS (4.46 ± 0.80%) than CSG-CON (7.92 ± 0.90%; P < 0.04), but not CSG-IRS (5.93 ± 1.04%); however, non-structural carbohydrates (NSC) did not differ (7.05 ± 0.62%). There were no differences in WSC (6.46 ± 0.54%) or NSC (7.65 ± 0.54%) by section type in LATE. Horses in IRS maintained a body condition score (BCS) of 5.78 ± 0.48, but BCS did not differ by system (CON: 6.11 ± 0.48). Thus, integrated grazing increased summer pasture yield and provided adequate nutrition to maintain horse condition, but further research is needed to improve late-season production. Integrated grazing may not, however, provide an advantage in limiting dietary NSC, as NSC remained low for all pasture sections.

Optimization Effects of Load Reduction for Earth Pressure on High-Filled Cut-and-Cover Tunnels Using the Discrete Element Method

In the Northwestern part of Loess Plateau of China, the ravine and valley are numerous; therefore, high-filled cut-and-cover tunnels (HFCCTs) play a major role in meeting traffic needs and creating a great deal of usable land. However, due to higher backfill soil, a high earth pressure is generated, which affects the safety of HFCCTs. To this end, using the discrete element method (DEM), three load reduction measures were introduced to evaluate HFCCT: the cross section types of HFCCT; the combination of optimized cross section type with load reduction using expanded polystyrene (EPS); and the combination of optimized cross section type with load reduction using the EPS and concrete wedge (CW). We evaluated changes in earth pressure of HFCCTs with reference to the density and laying position of EPS and the height as well as width of CW. Parametric DEM studies were performed to characterize these influential factors. It was found that different cross section types of HFCCT have a certain influence on earth pressure distribution, and load reduction effects of EPS were extremely obvious, resulting in a sharp drop in vertical earth pressure on top of HFCCT and a slight growth in lateral earth pressure on the sides of HFCCT. Moreover, installation of CWs reduced the VEP and LEP of HFCCT. These factors were also shown to exert important effects on load reduction mechanisms of HFCCT. Based on their influence on earth pressure of HFCCT from a macroscopic and microscopic view, optimal values for influential factors were derived.

Numerical modeling of an innovative arc shape rib based solar air heater

Solar air heating is a solar thermal technology wherein the sun energy is absorbed by an intermediate medium and utilized to heat air. In the present paper, a solar air heater equipped with innovative arc shaped ribs is considered. The heat transfer process in the proposed solar air heater is evaluated numerically for Reynolds numbers between 6000 and 12000. The influences of the rib cross section type, the inter-rib distance, the aspect ratio and the pitch of the ribs on the thermal efficiency of solar air heater are analyzed. Results indicate that firstly, ribs with quadrangular type of cross section exhibit the best coefficient of performance. Moreover, ribs with low pitch (40 mm) and aspect ratio equal to 0.5 show the highest thermal performance. Also, the effect of the distance between the ribs on the thermal efficiency of the considered solar air heater is insignificant. Finally, two correlations are obtained for the average Nusselt number and friction factor based on three dimensionless geometric factors.

An analytical stress model for composite multi-pinned plates considering the combination effects of pin load and bypass load in different positions

Multi-pin joints are commonly used in engineering due to their high loading capacity. However, affected by coupling relationships between pin load and bypass load, the evaluation of stress state is difficult for composite multi-pin joints. An analytical method is proposed in this paper to calculate stress distribution of these joints under tensile load. Stress functions in this method are created considering the pin load and bypass load, according to a geometry division of the whole plate. Superposition relationships are built for each section type with an influence coefficient of bypass load. Stress components could be obtained by calculation of stress functions when material properties, geometry dimension and load are known. Experiments and finite element method are employed to verify the validation of proposed method. Results show that pin position affects stress state, and mainly embodies in σx. The first pin always gets the highest stress level, while for the other pins the stress is quite similar. Increase pin number will decrease stress level but the effect is relatively small for the first pin.

Standardization of the Persian Version of the Self-Report Personality Questionnaire (SCID-5-SPQ) in a Clinical Sample of Iranian Population

Background and Aim: This study was conducted to investigate the psychometric characteristics of the Persian version of the self-report personality questionnaire (SCID-5-SPQ) in the clinical sample in Tehran. Method: The present study is descriptive cross section type. The present study population includes outpatients and inpatients referred to three centers in Tehran, including Iran Psychiatric Medical Center, Hazrat Rasool Akram Educational and Medical Complex and the Clinic of the Faculty of Behavioral Sciences andMental Health (Tehran Psychiatric Institute). .The criteria for entering the study were the ages between of 18 and 65, conscious consent to enter the study and the ability to understand and speak Persian and no specific physical problems. Sampling in this study was performed in Convenience Sampling manner. In this study, in addition to the demographic questionnaire, the Persian version of the Structured clinical interview for the DSM-5 (SCID-5) and the self-report personality questionnaire (SCID-5-SPQ) were used. Finally, in order to evaluate the information, formal and convergent validity methods, internal reliability and comparative tests were used. Results: Based on the results, the SCID-5-SPQ has a good formal narrative. A study of the convergent validity of this questionnaire with SCID interview showed that all subscales had a significant positive correlation (P≥0.001). Also, the reliability of the questionnaire was 0.93, and therefore the Persian version of this questionnaire is considered a stable tool. Conclusion: According to the findings of the present study, SCID-5-SPQ is a more stable tool and can be used in psychiatric clinics and hospitals as a screening tool for personality disorders alone or in addition to interviews.

Evaluation of Smeared Constitutive Laws for Tensile Concrete to Predict the Cracking of RC Beams under Torsion with Smeared Truss Model

In this study, the generalized softened variable angle truss-model (GSVATM) is used to predict the response of reinforced concrete (RC) beams under torsion at the early loading stages, namely the transition from the uncracked to the cracked stage. Being a 3-dimensional smeared truss model, the GSVATM must incorporate smeared constitutive laws for the materials, namely for the tensile concrete. Different smeared constitutive laws for tensile concrete can be found in the literature, which could lead to different predictions for the torsional response of RC beams at the earlier stages. Hence, the GSVATM is used to check several smeared constitutive laws for tensile concrete proposed in previous studies. The studied parameters are the cracking torque and the corresponding twist. The predictions of these parameters from the GSVATM are compared with the experimental results from several reported tests on RC beams under torsion. From the obtained results and the performed comparative analyses, one of the checked smeared constitutive laws for tensile concrete was found to lead to good predictions for the cracking torque of the RC beams regardless of the cross-section type (plain or hollow). Such a result could be useful to help with choosing the best constitutive laws to be incorporated into the smeared truss models to predict the response of RC beams under torsion.

Structural performance and section optimization of precast concrete sandwich panels with pin-type GFRP connectors

A precast concrete sandwich panel (PCSP) offers a good potential in the application of façade wall due to the improved energy efficiency. In this study, the structural performance of PCSP with pin-type glass fiber reinforced polymer (GFRP) connectors was investigated, and an optimization characterized by ribbed structural wythe was proposed and studied. Firstly, the pull-out and shear capacity of the pin-type connector were evaluated through direct tensile test and direct shear test, respectively. Thereafter, seven PCSP specimens were fabricated and tested under four points flexural load. The investigating parameters included the structural wythe thickness, loading direction, insulation bond, and section type of the structural wythe. The load-deflection relationship, crack pattern, failure mode, load-strain relationship, and degree of composite action of the PCSP were studied and compared. It was concluded that: (1) the tested PCSPs presented ductile failures; (2) the structural wythe thickness, loading direction and insulation bond would influence the cracking, yielding, and peak loads of the tested PCSP; (3) the PCSP with pin-type GFRP connectors could be designed as non-composite type owing to the low composite action; and (4) the proposed ribbed structural wythe could achieve a lightweight PCSP while considerable flexural stiffness and capacity could be retained.

Metal intensity of structural roof slab under different supporting conditions

The article presents and solves the problem of finding the design of minimum weight structural slab roof for given steel class, element cross-section type, and loading conditions. Structural roof slabs are widely used for large-span public and industrial buildings and allow a wide variety of structural and architectural forms. At the same time, the placement of supports was changed. In total, 10 options for the supports placement for the 36×36 m structural slab and 6 options for the topology were considered. After applying the load, structure’s strain-stress distribution was determined numerically, a cross-section was selected and its weight was calculated. Then, different options of support were compared in terms of structure weight. In fact, the article solved optimization problem by optimality criterion of metal intensity, restrictions in the form of overall dimensions, topology and strength conditions.