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Horizontal development of the cities has resulted in much destruction environmentally and economically. Two of the major consequences of such destruction is imbalanced development and inappropriate application of lands in the cities that are referred brownfield in this article. Brownfield in the urban planning jargon, a brownfield site (or simply a brownfield), is a type of land formerly used for industrial purposes or some commercial applications. The brownfield concept was first introduced by the British government and was used in accordance with the sustainable development policies which is mostly focused on the environmentally polluted lands. In the last two decades, redevelopment policies of brownfield as a crucial practical solution for preventing disperse growth of cities and also supporting the concentrated growth of cities have been attracted more attention. The main features of the brownfields are: -1 Pollution: each land in which an environmental complication has the occurrence probability. -2 Empty and leaved without using and in general lands and properties that their activities have been closed or not been used anymore. Of course, some of the terms that must be separated from the brownfield areas are: greenfields and grayfields.
Greenfields are those lands that previously has not been developed and often are rural or suburban. These green sites are located in the edge of small or large cities and have better accessibility and more palatability with additional space for future development.
The term grayfield, was defined in 1998 by new urbanism congress. Unlike the famous terms of greenfields (the rural undeveloped) and brownfields (polluted urban sites), the gray lands are called to the large undeveloped sites that have good reasons for redevelopment. The term of grayfield can be used to describe any kind of redevelopment that significantly is not polluted. But regarding the importance of environmental protection and sustainable development and realization their policies, it is essential to eliminate or reduce the environmental pollutions purposefully to achieve the redevelopment of brownfields.
For the sake of importance and novelty of the subject, redevelopment of Brownfield with the objective of efficient applications of lands in cities and reducing the environmental pollution and also improving the social-economical context of these fields is the subject of this article. Brownfield of Kan stream in Tehran was selected as the case study. The field was selected as it is one of the few major barren Brownfield in Tehran. They are not only in the leaved brownfields but also regarding the river-valley nature, the fields has specific ecological and tourism features. Unfortunately, due to lack of planning and management, these brownfields have been converted to the locations of rubbish depot and uncontrolled polluted waters and therefore infected with the environmental pollution. The methodology of this article is descriptiveanalytical using library studies. After studying the theoretical framework, defining features of brownfield, literature review, objectives and the importance and of these fields, the redevelopment process of Kan stream Brownfield are presented. Finally, the conclusion and analysis of the actions are conducted in redevelopment of brownfield with social, economical and tourism approach.
After comprehensive studies, in order to determine the kind of landuses in Kan brownfields, establishing a national and even an international performance scale park is designated as the planning vision. In this context, the objectives of the redevelopment planning process Kan brownfield included:
creating a touristic space to enhance the region›s tourism identity, planning with emphasis on providing recreational services for all social classes, such as children, elderly people and women and people with disabilities (all divisions with regard to sex, age and physical aspects), strengthening of the relationship between people and nature and to replacing normal social activities and improvement environmental conditions; Developing ecotourism in urban environment regarding and it s benefits beyond natural landscapes, enhancing green space for per capita in Tehran city and attainment to the standard limits for
environment qualities by using marginal lands and rivers sanctums.steel plates. In addition these bars are pre- tensioned by means of cable passing through them in order to behave properly to the applied forces.
The way that the bars are moved through the retraction process and the function of the building effects on the selection of the covering materials. In this structure, as the distance between the bars is changed during the deployment process it is required to use a flexible but strong material that can resist repeated retraction. Therefore, a flexible membrane that is strong enough during movement and has a proper foldability such as ETFE is one of the best alternatives for covering the roof. ETFE is also able to penetrate enough light inside of the building when the roof is in fully closed position and this in turn reduce the energy required for running the building.
The membrane is also attached to the bars though the slots that have already been created during fabrication and is fasted by means of pinned curve plate. This is also worth to mention that in this structure, the placement of the moveable components underneath the covering material support the whole structure even in severe weather conditions. Therefore, this increase the life cycle of the system and decrease the maintenance cost.
In summary, this paper proposes a new solution for a retractable curved roof system that can not only be transformed from an open to closed configuration but is also able to support itself structurally even during movement and transformation. In other word, the structural and transformable components are integrated and are able to make the whole structure stable during transformation.

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This paper attempts to explain the relationship between the imperative paradigm and the system of tense, aspect, and modality in Kurdish. This study employs the theoretical framework proposed by Aikhenvald and Dixon (2017). Additionally, the data were collected by interviewing Kurdish informants. The results indicate that the imperative paradigm in Kurdish is based on three imperative constructions, and four imperative strategies are also used to convey directive meanings. The results also show that the imperative constructions have different syntactic behaviors in different temporal zones of the tense system. The imperative constructions mainly combine with verbs that have a positive dynamic aspectual feature; however, these constructions transform these verbs during the process of coercion and highlight only the preparatory phases of the verbs. Consequently, these constructions combine easily with ingressive verbal operators because they represent only the preparatory phases of the actions. However, the imperative constructions do not combine with imperfective operators as they highlight the middle phases of the events. Furthermore, the imperative constructions do not host perfective aspectual operators due to semantic incongruity between them. Finally, the results show that the imperative constructions and strategies lack a rich eventual semantic layer and appear mainly as expressive speech acts.

1. Introduction
The tripartite system of tense, aspect, and mood constructs the composite eventual and modal structure of a sentence. However, this composite system manifests differently in various sentential types such as declarative, interrogative, and imperative. Although the interaction of these three subsystems has been extensively studied in declarative sentences, they have not been adequately explored in imperative constructions. Given the highly particular and idiosyncratic syntactic and semantic behavior of imperatives, it is crucial to study these subsystems and their interactions within imperative sentences. This paper aims to examine these subsystems and their interactions within the imperative paradigm, employing the theoretical framework proposed by Aikhenvald and Dixon (2017). Thus, it studies tense, aspect, and modality in canonical and non-canonical imperative constructions in Kurdish.

2. Literature Review
Imperative constructions have not been extensively investigated in Iranian languages in general, and Kurdish in particular. Most traditional grammatical sources in Kurdish adopt a prescriptive approach, primarily focusing on declarative and interrogative constructions and largely ignoring imperatives (IKSA 1976, 1985; Nabaz 1976; Mahvi 2011). No research to date has investigated tense, aspect, and modality in imperative constructions. However, Veisi Hasar (2021) studied imperative constructions in Kurdish, identifying two imperative constructions and four imperative strategies. Yet, he does not explore aspect, modality, and tense within these structures.

3. Methodology
The theoretical approach used in this study is based on the work of Aikhenvald and Dixon (2017) and the typological approach of Van der Auwera et al. (2005). Aikhenvald and Dixon (2017) categorize imperative constructions into canonical and non-canonical types. The canonical construction refers to the imperative for the second person singular subject. According to them, any structure derived from and matching the canonical construction can be considered an imperative construction. However, a non-canonical imperative, whose primary function is to express a directive function but structurally differs from the canonical construction, should be in complementary distribution with the canonical ones. If a directive structure is not structurally related to the canonical construction and is not in complementary distribution with it, it is not an imperative construction but an imperative strategy. In addition, based on the typological framework presented by Van der Auwera et al. (2005), we explain the imperative paradigm in Kurdish. This model illustrates different imperative paradigms as follows: 
- a. The language has a maximal system, but not a minimal one.
- b. The language has a minimal system, but not a maximal one.
- c. The language has both a maximal and a minimal system.
- d. The language has neither a maximal nor a minimal system.

4. Findings
By analyzing the data, it is revealed that the Kurdish language has three imperative constructions and four imperative strategies. The second person singular imperative is formed by a special inflectional ending, an omitted subject, and a subjunctive mood indicated by the prefix -bǝ. The second person plural imperative uses a deleted subject and the prefix -bǝ, but lacks a special verbal ending. Imperative constructions for other person-number categories (first, third, singular, and plural) use a specific imperative operator bā and the prefix -bǝ. These three constructions form the imperative paradigm in Kurdish. Additionally, four strategies are used to express commands and directive meanings, which are not syntactically imperative. These constructions are based on the verbs heŝtәn (let), řoʔin (going), and hātәn (come), each possessing distinct grammatical attributes and used in various contexts.
Regarding the interaction between imperatives and tense, imperative constructions are mainly bound to the present tense and do not appear in other tenses. Interestingly, even the imperative strategies are primarily limited to the present tense and do not convey commands in other tenses. Only the second person singular imperative can appear in the future tense, in contrast to other categories, and takes a different inflectional ending.
Imperative constructions predominantly combine verbs that have a dynamic aspectual feature. However, through coercion, they highlight only the preparatory phase of these verbs. Static verbs within this construct are marked. Dynamic verbs in an imperative structure undergo coercion, and only their preparatory phases are highlighted in the imperative construct. Regarding grammatical aspects, imperative verbs do not combine with imperfective (progressive) verbs, as they do not profile the middle phases indicated by the progressive operators. Instead, they combine with ingressive operators, as both highlight the preparatory phases of the verbs. Additionally, imperative constructions do not combine perfective verbs due to semantic incompatibility. The perfective operator refers to a bounded process, while imperative constructs do not profile the ending limitation of the verbs.