SOME RESULTS ON INTEGER-VALUED POLYNOMIALS OVER MODULES

Naghipour, Ali Reza,Hafshejani, Javad Sedighi Korean Mathematical Society 2020 대한수학회보 Vol.57 No.5

Let M be a module over a commutative ring R. In this paper, we study Int(R, M), the module of integer-valued polynomials on M over R, and Int_M(R), the ring of integer-valued polynomials on R over M. We establish some properties of Krull dimensions of Int(R, M) and Int_M(R). We also determine when Int(R, M) and Int_M(R) are nontrivial. Among the other results, it is shown that Int(ℤ, M) is not Noetherian module over Int_M(ℤ) ∩ Int(ℤ), where M is a finitely generated ℤ-module.

A GENERALIZATION OF THE JACOBSON RADICAL

Naghipour, A.R.,Yamini, A.H. Korean Mathematical Society 2004 대한수학회보 Vol.41 No.4

Let R be an associative ring with identity and J(R) be the Jacobson radical of R. In this paper we investigate the generalization of the Jacobson radical of R, J* (R) say. Also we study the rings that J*(R) = J(R).

Comparison of lidocaine with articaine buccal injection in reducing complications following impacted mandibular third molar surgery: a split-mouth randomized clinical trial

Naghipour, Amin,Esmaeelinejad, Mohammad,Dehnad, Seyed Vahid,Shahi, Anahita,Jarrahi, Alireza The Korean Dental Society of Anesthsiology 2020 Journal of Dental Anesthesia and Pain Medicine Vol.20 No.4

Background: Complications following impacted third molar surgery significantly affect patients' quality of life during the immediate postoperative period. This study aimed to achieve the proper anesthesia method by comparing the effect of the application of lidocaine alone with the application of lidocaine and articaine simultaneously in reducing the complications during and following impacted mandibular third molar surgery. Methods: The study design was a split-mouth double-blind randomized clinical trial. The study was conducted on 13 patients (26 samples) referred for elective surgical removal of bilateral impacted mandibular third molar with similar difficulty on both sides. Each patient underwent similar surgical procedures on two separate appointments. Each patient randomly received 2% lidocaine for conventional inferior alveolar nerve block and 4% articaine for local infiltration before the surgery on one side (group A) and 2% lidocaine alone (for both block anesthesia and infiltration) before the surgery on the other side (group B). Intraoperative and postoperative variables for both groups were established and statistically analyzed. Results: The findings showed that pain on the first day after surgery in group A was significantly lower than that in group B. The patients in group A mentioned experiencing less discomfort following the surgery. The increased horizontal swelling on the first and third days following surgery and oblique swelling on the seventh day in patients in group B were statistically significant. Conclusion: Choosing an appropriate anesthetic drug for oral surgery, specifically impacted third molar surgery, is dependent on the clinician's opinion, however; it seems that the combination of lidocaine and articaine may control the patient's pain significantly better than lidocaine alone.

A REFINEMENT OF THE UNIT AND UNITARY CAYLEY GRAPHS OF A FINITE RING

Naghipour, Ali Reza,Rezagholibeigi, Meysam Korean Mathematical Society 2016 대한수학회보 Vol.53 No.4

Let R be a finite commutative ring with nonzero identity. We define ${\Gamma}(R)$ to be the graph with vertex set R in which two distinct vertices x and y are adjacent if and only if there exists a unit element u of R such that x + uy is a unit of R. This graph provides a refinement of the unit and unitary Cayley graphs. In this paper, basic properties of ${\Gamma}(R)$ are obtained and the vertex connectivity and the edge connectivity of ${\Gamma}(R)$ are given. Finally, by a constructive way, we determine when the graph ${\Gamma}(R)$ is Hamiltonian. As a consequence, we show that ${\Gamma}(R)$ has a perfect matching if and only if ${\mid}R{\mid}$ is an even number.

Evaluation of dynamic properties of extra light weight concrete sandwich beams reinforced with CFRP

M. Naghipour,M. Mehrzadi 국제구조공학회 2007 Steel and Composite Structures, An International J Vol.7 No.6

Analytical and experimental investigation on dynamic properties of extra lightweight concrete sandwich beams reinforced with various lay ups of carbon reinforced epoxy polymer composites (CFRP) are discussed. The lightweight concrete used in the core of the sandwich beams was made up of extra lightweight aggregate, Lica. The density of concrete was half of that of the ordinary concrete and its compressive strength was about 100 Kg/cm2. Two extra lightweight unreinforced (control) beams and six extra lightweight sandwich beams with various lay ups of CFRP were clamped in one end and tested under an impact load. The dimension of the beams without considering any reinforcement was 20 cm × 10 cm × 1.4 m. These were selected to ensure that the effect of shear during the bending test would be minimized. Three other beams, made up of ordinary concrete reinforced with steel bars, were tested in the same conditions. For measuring the damping capacity of sandwich beams three methods, Logarithmic Decrement Analysis (LDA), Hilbert Transform Analysis (HTA) and Moving Block Analysis (MBA) were applied. The first two methods are in time domain and the last one is in frequency domain. A comparison between the damping capacity of the beams obtained from all three methods, shows that the damping capacity of the extra lightweight concrete decreases by adding the composite reinforced layers to the upper and lower sides of the beams, and becomes most similar to the damping of the ordinary beams. Also the results show that the stiffness of the extra lightweight concrete beams increases by adding the composite reinforced layer to their both sides and become similar to the ordinary beams.

Experimental investigation of natural bond behavior in circular CFTs

Morteza Naghipour,Aidin Khalili,Seyed Mohammad Reza Hasani,Mahdi Nematzadeh 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.2

Undoubtedly, the employment of direct bond interaction between steel and concrete is preceding the other mechanisms because of its ease of construction. However, the large scatter in the experimental data about the issue has hindered the efforts to characterize bond strength. In the following research, the direct bond interaction and bond-slip behavior of CFTs with circular cross-section were examined through repeated load-reversed push-out tests until four cycles of loading. The influence of different parameters including the diameter of the tube and the use of shear tabs were assessed. Moreover, the utilization of expansive concrete and external spirals was proposed and tested as ways of improving bond strength. According to the results section dimensions, tube slenderness, shrinkage potential of concrete, interface roughness and confinement are key factors in a natural bond. Larger diameters will lead to a considerable drop in bond strength. The use of shear tabs by their associated bending moments increases the bond stress up to eight times. Furthermore, employment of external spirals and expansive concrete have a sensible effect on enhancing bonds. Macro-locking was also found to be the main component in achieving bond strength.

Experimental study on axial compressive behavior of welded built-up CFT stub columns made by cold-formed sections with different welding lines

Morteza Naghipour,Ghazaleh Yousofizinsaz,Mahdi Shariati 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.3

The objective of this study is to experimentally scrutinize the axial performance of built-up concrete filled steel tube (CFT) columns composed of steel plates. In this case, the main parameters cross section types, compressive strength of filled concrete, and the effect of welding lines. Welded built-up steel box columns are fabricated by connecting two pieces of cold-formed U-shaped or four pieces of L-shaped thin steel plates with continuous penetration groove welding line located at mid-depth of stub column section. Furthermore, traditional square steel box sections with no welding lines are investigated for the comparison of axial behavior between the generic and build-up cross sections. Accordingly, 20 stub columns with thickness and height of 2 and 300 mm have been manufactured. As a result, welding lines in built-up specimens act as stiffeners because have higher strength and thickness in comparison to the plates. Subsequently, by increasing the welding lines, the load bearing capacity of stub columns has been increased in comparison to the traditional series. Furthermore, for specimens with the same confinement steel tubes and concrete core, increment of B/t ratio has reduced the ductility and axial strength.

Effect of progressive shear punch of a foundation on a reinforced concrete building behavior

Morteza Naghipour,Kia Moghaddas Niak,Mahdi Shariati,Ali Toghroli 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.2

Foundation of a building is damaged under service loads during construction. First visit shows that the foundation has been punched at the 6 column’s foot region led to building rotation. Foundation shear punching occurring has made some stresses and deflections in construction. In this study, progressing of damage caused by foundation shear punching and inverse loading in order to resolve the building rotation has been evaluated in the foundation and frame of building by finite element modeling in ABAQUS software. The stress values of bars in punched regions of foundation has been deeply exceeded from steel yielding strength and experienced large displacement based on software’s results. On the other hand, the values of created stresses in the frame are not too big to make serious damage. In the beams and columns of ground floor, some partial cracks has been occurred and in other floors, the values of stresses are in the elastic zone of materials. Finally, by inverse loading to the frame, the horizontal displacement of floors has been resolved and the values of stresses in frame has been significantly reduced.

Some results of monomial ideals on regular sequences

Reza Naghipour,Somayeh Vosughian 대한수학회 2021 대한수학회보 Vol.58 No.3

Let $R$ denote a commutative noetherian ring, and let ${\bf x} :=x_1,\ldots,x_d$ be an $R$-regular sequence. Suppose that $\mathfrak a$ denotes a monomial ideal with respect to ${\bf x}$. The first purpose of this article is to show that $\mathfrak a$ is irreducible if and only if $\mathfrak{a}$ is a generalized-parametric ideal. Next, it is shown that, for any integer $n\geq 1$, $(x_1,\ldots,x_d)^{n}=\bigcap {\bf P}(f),$ where the intersection (irredundant) is taken over all monomials $f=x_1^{e_1}\cdots x_d^{e_d}$ such that ${\rm deg}(f)=n-1$ and ${\bf P}(f):=(x_{1}^{e_{1}+1},\dots,x_{d}^{e_{d}+1})$. The second main result of this paper shows that if $\mathfrak q:=(\bf x)$ is a prime ideal of $R$ which is contained in the Jacobson radical of $R$ and $R$ is $\mathfrak q$-adically complete, then $\mathfrak{a}$ is a parameter ideal if and only if $\mathfrak{a}$ is a monomial irreducible ideal and ${\rm Rad}(\mathfrak{a})=\mathfrak q$. In addition, if $\mathfrak{a}$ is generated by monomials $m_{1},\dots, m_{r},$ then ${\rm Rad}(\mathfrak{a})$, the radical of $\mathfrak a$, is also monomial and ${\rm Rad}(\mathfrak{a})=(\omega_{1},\dots, \omega_{r})$, where $\omega_i={\rm rad}(m_i)$ for all $i=1, \dots, r$.

A generalization of the Jacobson radical

A. R. Naghipour,A. H. Yamini 대한수학회 2004 대한수학회보 Vol.41 No.4

Let R be an associative ring with identity and J(R) be theJacobson radical of R. In this paper we investigate thegeneralization of the Jacobson radical of R, J^{*}(R) say.Also we study the rings that J^{*}(R)=J(R).