The recession cone and recession function are very important research objects in Convex Analysis. They have extensive applications in the optimization theory. Firstly, we study the properties of the recession cone and recession function. The positive homogeneity and subadditivity of recession function are mainly discussed. And the different methods are considered to prove these properties. Secondly, we discuss the unboundedness of the convex sets and convex functions by using recession cone and recession function.

Weather is almost inevitable and plays an important role in determining the duration of construction projects. The construction industry ultimately thrives upon the physical input, put in by the labours. The majority of the construction projects are executed in the outdoor environment and hence face a high impact of weather conditions. This study therefore evaluated the influence of weather conditions on construction workers’ productivity in Jos, Plateau State and proceeded to make recommendations geared towards the improvement of construction workers’ productivity in Jos. The study was conducted through the direct observation method. Three hundred and ninety-six (396) works were purposively sampled in selected working sites. The outcome shows that during dry weather, there was considerably less significant productivity of manual excavation. In contrast, a large increase in blockwork and plasterwork productivity was observed with a percentage difference of 33%, 56.3% and 61%, respectively. On the other hand, during wet weather conditions, the labour productivity for manual excavation increases, whereas it decreases for block work and plasterwork with percentages difference of 58%, 40% and 47%, respectively. Besides, relative humidity and wind speed have no impact on labours’ productivity in dry and wet weather. Besides, the temperature has the most decisive impact on workers’ productivity. Moreover, wind speed and humidity have a lower influence on workers’ productivity. The construction industry stakeholder in Jos, Nigeria, would benefit from this study’s recommendations for reducing the influence of weather on the building sector. Besides, the output can be extended to other regions having similar characteristics.

Project success requires team commitment, which is a product of an encouraging culture of cooperation and teamwork among project team members. The research work aims to ascertain which components of team commitment affect the performance of construction projects in Nigeria. The research adopted a quantitative design where questionnaires were used for data collection. Out of 1233 questionnaires distributed, 975 were received with valid responses and used for data analysis. Data were analysed descriptively using percentage, mean score, and relative agreement index. The study showed the factors of team commitment having an effect on project performance, as rated by the respondents, to be: Normative component: “Project team members owe a great deal to this organisation”; “Members of the project team do not feel it is right to quit the project before completion”; “This organisation has a great deal of personal meaning for project team members”. Affective component: “This organisation deserves the loyalty of project team members”; “The project team considers the team’s problems as their own. Then, “One of the few negative consequences of leaving this organisation will be the scarcity of available alternatives” is for continuance. In conclusion, the emotional attachment of the team members and sense of obligation to the project team and construction organisation are the driving forces behind pushing for the successful outcome of projects within the Nigerian construction industry.