zaid alzaidi - Academia.edu (original) (raw)
Papers by zaid alzaidi
Failure to meet the deadlines for the implementation of investment and construction projects is a... more Failure to meet the deadlines for the implementation of investment and construction projects is a problem in all countries of the world, and leads to unstable activity of construction companies. The article studies the most important destabilizing factors affecting the main indicator of sustainable activity of construction companies-the duration of the implementation of an investment and construction projects. To determine and assess the impact of destabilizing factors on the duration of implementation of selected investment and construction projects, a survey was conducted, in which a number of customers, consultants and contractors involved in construction projects took part. Questionnaires developed on the basis of a cluster sample were sent to respondents, 48 responses were received in response to the assessment of destabilizing factors. To analyze the received and grouped information, structural equation modeling using the Smart-PLS program was used. As a result of modeling, a ...
Sustainability is a characteristic manifested in the ability to maintain the necessary level of p... more Sustainability is a characteristic manifested in the ability to maintain the necessary level of performance for construction companies when risk factors arise during the implementation of investment and construction projects. The risk factors that arise during the implementation of in-vestment and construction projects differ in nature, degree of influence, and other characteristics. Ignoring these factors and measures to manage them often leads to critical consequences in the form of disruptions in the timing of work. Risk is a combination of the probability and consequences of the occurrence of adverse events. The article considers the concept of risk as a potential possibility of occurrence of adverse situations and related consequences when exposed to these factors. Risk factors are characterized by surprise, discreteness of changes, the presence of threshold values, upon reaching which a transition to a different mode of operation is required. The article discusses the risk fac...
Buildings
Construction production in Russia and abroad (in Iraq) is facing various negative factors. The em... more Construction production in Russia and abroad (in Iraq) is facing various negative factors. The emergence of diverse factors in the implementation of investment and construction projects has an effect on the making of important decisions by the heads of construction enterprises, which may in the future be the cause of uncertainty and, as a result, the emergence of critical risks. The purpose of the study is to develop a methodology for identifying and assessing the influence of risk factors on the activities of construction enterprises in the implementation of investment projects. For the purposes of the study, mathematical and statistical models were used, such as the hierarchical analysis method and Monte Carlo, as well as the expert survey. The result of the study shows that the use of those models will significantly increase the success of construction enterprises by identifying various risk factors at the stage of construction and assessing their impact on these projects. The sc...
目的 观察吡咯烷二硫代氨基甲酯(PDTC)对大鼠颈椎动力失衡模型颈椎间盘组织形态及肿瘤坏死因子α(TNF-α)、基质金属蛋白酶9(MMP-9) 表达的影响，探讨PDTC抑制颈椎间盘退变作用及其机... more 目的 观察吡咯烷二硫代氨基甲酯(PDTC)对大鼠颈椎动力失衡模型颈椎间盘组织形态及肿瘤坏死因子α(TNF-α)、基质金属蛋白酶9(MMP-9) 表达的影响，探讨PDTC抑制颈椎间盘退变作用及其机制。 方法 54只SD大鼠随机分为3组，切断大鼠颈后部浅、深肌群构建颈椎间盘退变动物模型。PDTC给药组(A组)：造模术后腹腔每日注射PDTC溶液。模型组(B组)：造模术后腹腔每日注射生理盐水。假手术组(C组)：手术切开大鼠颈后部皮肤后立即缝合并每日腹腔注射生理盐水。术后10、12、16周分批处死动物，获取C5/6椎间盘组织，光镜下观察椎间盘形态改变，q-PCR检测椎间盘组织中TNF-α mRNA、MMP-9 mRNA表达；Western blot检测椎间盘组织中TNF-α、MMP-9蛋白表达变化。 结果 PDTC给药组(A组)椎间盘结构破坏减轻，纤维环结构排列有序。模型组(B组)TNF-α、MMP-9基因表达量随实验时间的延长而增多，早期增速较快，后期逐渐缓慢，在12周达高峰，而蛋白表达量在术后10周即达到较高水平，与12周、16周时间点比较无明显差异(P＞0.05)。各时间点PDTC给药组TNF-α mRNA、MMP-9 mRNA及蛋白表达量较模型组(B组)明显降低(P＜0.01)，但明显高于假手术组(P＜0.01)。 结论 TNF-α、MMP-9是参与大鼠颈椎间盘退变过程的重要炎性因子，TNF-α、MMP-9可能通过NF-κB信号通路参与大鼠颈椎间盘退变，PDTC有望成为颈椎间盘退变的防治药物。
International Journal of Engineering & Technology, Nov 28, 2018
The effect of retarding admixture on the fresh and hardened behaviour of different types of cemen... more The effect of retarding admixture on the fresh and hardened behaviour of different types of cement mortars and pastes when using a retarding admixture was investigated in this study. The types of cement used are; White cement (WhC), Ordinary Portland cement (OPC) and Sulphate Resistant Portland cement (SRC). Different cement mortar and paste mixes were cast, for this purpose, with and without the admixture. Initial and final setting times, compressive strength, length change, absorption and density for these mixes were examined at the curing ages of 3,7,28,45 days. The results showed that the addition of retarding admixture delayed the setting time significantly of WhC paste. The retarding admixture has a positive effect on the compressive strength of the mortar specimens for all types of cement used. regarding the length change test, the admixture was found to reduce the initial expansion for all types of cement at all ages. The results also showed an increase in the density and decrease in water absorption, especially at the later ages for all types of cement. Among all cement types used, WhC was noticeably the most affected type by using the retarding admixture compared to other types of cement used.
In this study, composite columns have been tested under axial load. The steel tubes were filled w... more In this study, composite columns have been tested under axial load. The steel tubes were filled with waste concrete to perform the composite action. The specimens divided into two groups; square and circular columns. The diameter of the circular hallow columns was 7.5 cm with 2mm thickness, while the dimension of the square hallow columns was (7.5 cm × 7.5 cm) with 2mm thickness. For each group a column without waste concrete filled steel tubular (W.C.F.S.T) was tested to act as a reference column. Load-deflection curves were constructed for all specimens. The results indicate that the waste concrete filled steel tube has more capacity due to the composite action. The pattern of failure in circular sections was different from the failure pattern of the square ones.
International Journal of Engineering & Technology
Recent trends in lightweight concrete manufacturing have led to a proliferation of studies demons... more Recent trends in lightweight concrete manufacturing have led to a proliferation of studies demonstrating that wood aggregates can be used to produce sustainable green concrete composites. However, wood particles contain soluble substances (saccharides), which have a significant effect on the setting time of Portland cement. To attain a better understanding of this, two types of wood were treated in boiling water. After the treatment process, the resulting water (“boiling water of wood”) was used to study its effect on the initial setting time of Portland cement. The mechanical properties and the density were also investigated for concrete mixtures consisting of 0, 5, 7.5, and 10% treated wood particles (weight replacement from coarse aggregate). As a result, the effect of the wood’s soluble substances was determined and the optimum mix proportion was chosen for achieving the minimum nominal density and the best mechanical properties.
International Journal of Engineering & Technology
The effect of retarding admixture on the fresh and hardened behaviour of different types of cemen... more The effect of retarding admixture on the fresh and hardened behaviour of different types of cement mortars and pastes when using a retarding admixture was investigated in this study. The types of cement used are; White cement (WhC), Ordinary Portland cement (OPC) and Sulphate Resistant Portland cement (SRC). Different cement mortar and paste mixes were cast, for this purpose, with and without the admixture. Initial and final setting times, compressive strength, length change, absorption and density for these mixes were examined at the curing ages of 3,7,28,45 days. The results showed that the addition of retarding admixture delayed the setting time significantly of WhC paste. The retarding admixture has a positive effect on the compressive strength of the mortar specimens for all types of cement used. regarding the length change test, the admixture was found to reduce the initial expansion for all types of cement at all ages. The results also showed an increase in the density and de...
Failure to meet the deadlines for the implementation of investment and construction projects is a... more Failure to meet the deadlines for the implementation of investment and construction projects is a problem in all countries of the world, and leads to unstable activity of construction companies. The article studies the most important destabilizing factors affecting the main indicator of sustainable activity of construction companies-the duration of the implementation of an investment and construction projects. To determine and assess the impact of destabilizing factors on the duration of implementation of selected investment and construction projects, a survey was conducted, in which a number of customers, consultants and contractors involved in construction projects took part. Questionnaires developed on the basis of a cluster sample were sent to respondents, 48 responses were received in response to the assessment of destabilizing factors. To analyze the received and grouped information, structural equation modeling using the Smart-PLS program was used. As a result of modeling, a ...
Sustainability is a characteristic manifested in the ability to maintain the necessary level of p... more Sustainability is a characteristic manifested in the ability to maintain the necessary level of performance for construction companies when risk factors arise during the implementation of investment and construction projects. The risk factors that arise during the implementation of in-vestment and construction projects differ in nature, degree of influence, and other characteristics. Ignoring these factors and measures to manage them often leads to critical consequences in the form of disruptions in the timing of work. Risk is a combination of the probability and consequences of the occurrence of adverse events. The article considers the concept of risk as a potential possibility of occurrence of adverse situations and related consequences when exposed to these factors. Risk factors are characterized by surprise, discreteness of changes, the presence of threshold values, upon reaching which a transition to a different mode of operation is required. The article discusses the risk fac...
Buildings
Construction production in Russia and abroad (in Iraq) is facing various negative factors. The em... more Construction production in Russia and abroad (in Iraq) is facing various negative factors. The emergence of diverse factors in the implementation of investment and construction projects has an effect on the making of important decisions by the heads of construction enterprises, which may in the future be the cause of uncertainty and, as a result, the emergence of critical risks. The purpose of the study is to develop a methodology for identifying and assessing the influence of risk factors on the activities of construction enterprises in the implementation of investment projects. For the purposes of the study, mathematical and statistical models were used, such as the hierarchical analysis method and Monte Carlo, as well as the expert survey. The result of the study shows that the use of those models will significantly increase the success of construction enterprises by identifying various risk factors at the stage of construction and assessing their impact on these projects. The sc...
目的 观察吡咯烷二硫代氨基甲酯(PDTC)对大鼠颈椎动力失衡模型颈椎间盘组织形态及肿瘤坏死因子α(TNF-α)、基质金属蛋白酶9(MMP-9) 表达的影响，探讨PDTC抑制颈椎间盘退变作用及其机... more 目的 观察吡咯烷二硫代氨基甲酯(PDTC)对大鼠颈椎动力失衡模型颈椎间盘组织形态及肿瘤坏死因子α(TNF-α)、基质金属蛋白酶9(MMP-9) 表达的影响，探讨PDTC抑制颈椎间盘退变作用及其机制。 方法 54只SD大鼠随机分为3组，切断大鼠颈后部浅、深肌群构建颈椎间盘退变动物模型。PDTC给药组(A组)：造模术后腹腔每日注射PDTC溶液。模型组(B组)：造模术后腹腔每日注射生理盐水。假手术组(C组)：手术切开大鼠颈后部皮肤后立即缝合并每日腹腔注射生理盐水。术后10、12、16周分批处死动物，获取C5/6椎间盘组织，光镜下观察椎间盘形态改变，q-PCR检测椎间盘组织中TNF-α mRNA、MMP-9 mRNA表达；Western blot检测椎间盘组织中TNF-α、MMP-9蛋白表达变化。 结果 PDTC给药组(A组)椎间盘结构破坏减轻，纤维环结构排列有序。模型组(B组)TNF-α、MMP-9基因表达量随实验时间的延长而增多，早期增速较快，后期逐渐缓慢，在12周达高峰，而蛋白表达量在术后10周即达到较高水平，与12周、16周时间点比较无明显差异(P＞0.05)。各时间点PDTC给药组TNF-α mRNA、MMP-9 mRNA及蛋白表达量较模型组(B组)明显降低(P＜0.01)，但明显高于假手术组(P＜0.01)。 结论 TNF-α、MMP-9是参与大鼠颈椎间盘退变过程的重要炎性因子，TNF-α、MMP-9可能通过NF-κB信号通路参与大鼠颈椎间盘退变，PDTC有望成为颈椎间盘退变的防治药物。
International Journal of Engineering & Technology, Nov 28, 2018
The effect of retarding admixture on the fresh and hardened behaviour of different types of cemen... more The effect of retarding admixture on the fresh and hardened behaviour of different types of cement mortars and pastes when using a retarding admixture was investigated in this study. The types of cement used are; White cement (WhC), Ordinary Portland cement (OPC) and Sulphate Resistant Portland cement (SRC). Different cement mortar and paste mixes were cast, for this purpose, with and without the admixture. Initial and final setting times, compressive strength, length change, absorption and density for these mixes were examined at the curing ages of 3,7,28,45 days. The results showed that the addition of retarding admixture delayed the setting time significantly of WhC paste. The retarding admixture has a positive effect on the compressive strength of the mortar specimens for all types of cement used. regarding the length change test, the admixture was found to reduce the initial expansion for all types of cement at all ages. The results also showed an increase in the density and decrease in water absorption, especially at the later ages for all types of cement. Among all cement types used, WhC was noticeably the most affected type by using the retarding admixture compared to other types of cement used.
In this study, composite columns have been tested under axial load. The steel tubes were filled w... more In this study, composite columns have been tested under axial load. The steel tubes were filled with waste concrete to perform the composite action. The specimens divided into two groups; square and circular columns. The diameter of the circular hallow columns was 7.5 cm with 2mm thickness, while the dimension of the square hallow columns was (7.5 cm × 7.5 cm) with 2mm thickness. For each group a column without waste concrete filled steel tubular (W.C.F.S.T) was tested to act as a reference column. Load-deflection curves were constructed for all specimens. The results indicate that the waste concrete filled steel tube has more capacity due to the composite action. The pattern of failure in circular sections was different from the failure pattern of the square ones.
International Journal of Engineering & Technology
Recent trends in lightweight concrete manufacturing have led to a proliferation of studies demons... more Recent trends in lightweight concrete manufacturing have led to a proliferation of studies demonstrating that wood aggregates can be used to produce sustainable green concrete composites. However, wood particles contain soluble substances (saccharides), which have a significant effect on the setting time of Portland cement. To attain a better understanding of this, two types of wood were treated in boiling water. After the treatment process, the resulting water (“boiling water of wood”) was used to study its effect on the initial setting time of Portland cement. The mechanical properties and the density were also investigated for concrete mixtures consisting of 0, 5, 7.5, and 10% treated wood particles (weight replacement from coarse aggregate). As a result, the effect of the wood’s soluble substances was determined and the optimum mix proportion was chosen for achieving the minimum nominal density and the best mechanical properties.
International Journal of Engineering & Technology
The effect of retarding admixture on the fresh and hardened behaviour of different types of cemen... more The effect of retarding admixture on the fresh and hardened behaviour of different types of cement mortars and pastes when using a retarding admixture was investigated in this study. The types of cement used are; White cement (WhC), Ordinary Portland cement (OPC) and Sulphate Resistant Portland cement (SRC). Different cement mortar and paste mixes were cast, for this purpose, with and without the admixture. Initial and final setting times, compressive strength, length change, absorption and density for these mixes were examined at the curing ages of 3,7,28,45 days. The results showed that the addition of retarding admixture delayed the setting time significantly of WhC paste. The retarding admixture has a positive effect on the compressive strength of the mortar specimens for all types of cement used. regarding the length change test, the admixture was found to reduce the initial expansion for all types of cement at all ages. The results also showed an increase in the density and de...